diff --git a/content/base/src/Element.cpp b/content/base/src/Element.cpp
index 1a71b647edb7..bc32217e91d3 100644
--- a/content/base/src/Element.cpp
+++ b/content/base/src/Element.cpp
@@ -1595,7 +1595,7 @@ Element::DispatchClickEvent(nsPresContext* aPresContext,
   NS_PRECONDITION(aSourceEvent, "Must have source event");
   NS_PRECONDITION(aStatus, "Null out param?");
 
-  nsMouseEvent event(NS_IS_TRUSTED_EVENT(aSourceEvent), NS_MOUSE_CLICK,
+  nsMouseEvent event(aSourceEvent->mFlags.mIsTrusted, NS_MOUSE_CLICK,
                      aSourceEvent->widget, nsMouseEvent::eReal);
   event.refPoint = aSourceEvent->refPoint;
   uint32_t clickCount = 1;
@@ -2311,7 +2311,7 @@ Element::CheckHandleEventForLinksPrecondition(nsEventChainVisitor& aVisitor,
                                               nsIURI** aURI) const
 {
   if (aVisitor.mEventStatus == nsEventStatus_eConsumeNoDefault ||
-      (!NS_IS_TRUSTED_EVENT(aVisitor.mEvent) &&
+      (!aVisitor.mEvent->mFlags.mIsTrusted &&
        (aVisitor.mEvent->message != NS_MOUSE_CLICK) &&
        (aVisitor.mEvent->message != NS_KEY_PRESS) &&
        (aVisitor.mEvent->message != NS_UI_ACTIVATE)) ||
@@ -2446,7 +2446,7 @@ Element::PostHandleEventForLinks(nsEventChainPostVisitor& aVisitor)
       if (shell) {
         // single-click
         nsEventStatus status = nsEventStatus_eIgnore;
-        nsUIEvent actEvent(NS_IS_TRUSTED_EVENT(aVisitor.mEvent),
+        nsUIEvent actEvent(aVisitor.mEvent->mFlags.mIsTrusted,
                            NS_UI_ACTIVATE, 1);
 
         rv = shell->HandleDOMEventWithTarget(this, &actEvent, &status);
@@ -2463,7 +2463,8 @@ Element::PostHandleEventForLinks(nsEventChainPostVisitor& aVisitor)
         nsAutoString target;
         GetLinkTarget(target);
         nsContentUtils::TriggerLink(this, aVisitor.mPresContext, absURI, target,
-                                    true, true, NS_IS_TRUSTED_EVENT(aVisitor.mEvent));
+                                    true, true,
+                                    aVisitor.mEvent->mFlags.mIsTrusted);
         aVisitor.mEventStatus = nsEventStatus_eConsumeNoDefault;
       }
     }
diff --git a/content/base/src/nsContentUtils.cpp b/content/base/src/nsContentUtils.cpp
index 93dfd7e9eb67..84590e13aae9 100644
--- a/content/base/src/nsContentUtils.cpp
+++ b/content/base/src/nsContentUtils.cpp
@@ -5339,7 +5339,7 @@ nsContentUtils::GetDragSession()
 nsresult
 nsContentUtils::SetDataTransferInEvent(nsDragEvent* aDragEvent)
 {
-  if (aDragEvent->dataTransfer || !NS_IS_TRUSTED_EVENT(aDragEvent))
+  if (aDragEvent->dataTransfer || !aDragEvent->mFlags.mIsTrusted)
     return NS_OK;
 
   // For draggesture and dragstart events, the data transfer object is
diff --git a/content/events/src/nsAsyncDOMEvent.cpp b/content/events/src/nsAsyncDOMEvent.cpp
index 87fc0d190dc8..bb185d581262 100644
--- a/content/events/src/nsAsyncDOMEvent.cpp
+++ b/content/events/src/nsAsyncDOMEvent.cpp
@@ -13,12 +13,11 @@
 nsAsyncDOMEvent::nsAsyncDOMEvent(nsINode *aEventNode, nsEvent &aEvent)
   : mEventNode(aEventNode), mDispatchChromeOnly(false)
 {
-  bool trusted = NS_IS_TRUSTED_EVENT(&aEvent);
   nsEventDispatcher::CreateEvent(nullptr, &aEvent, EmptyString(),
                                  getter_AddRefs(mEvent));
   NS_ASSERTION(mEvent, "Should never fail to create an event");
   mEvent->DuplicatePrivateData();
-  mEvent->SetTrusted(trusted);
+  mEvent->SetTrusted(aEvent.mFlags.mIsTrusted);
 }
 
 NS_IMETHODIMP nsAsyncDOMEvent::Run()
diff --git a/content/events/src/nsDOMEvent.cpp b/content/events/src/nsDOMEvent.cpp
index 96992de7e267..24caa2b56004 100644
--- a/content/events/src/nsDOMEvent.cpp
+++ b/content/events/src/nsDOMEvent.cpp
@@ -267,12 +267,7 @@ nsDOMEvent::GetOriginalTarget(nsIDOMEventTarget** aOriginalTarget)
 NS_IMETHODIMP
 nsDOMEvent::SetTrusted(bool aTrusted)
 {
-  if (aTrusted) {
-    mEvent->flags |= NS_EVENT_FLAG_TRUSTED;
-  } else {
-    mEvent->flags &= ~NS_EVENT_FLAG_TRUSTED;
-  }
-
+  mEvent->mFlags.mIsTrusted = aTrusted;
   return NS_OK;
 }
 
@@ -426,8 +421,7 @@ nsDOMEvent::PreventCapture()
 NS_IMETHODIMP
 nsDOMEvent::GetIsTrusted(bool *aIsTrusted)
 {
-  *aIsTrusted = NS_IS_TRUSTED_EVENT(mEvent);
-
+  *aIsTrusted = mEvent->mFlags.mIsTrusted;
   return NS_OK;
 }
 
@@ -438,8 +432,7 @@ nsDOMEvent::PreventDefault()
     mEvent->flags |= NS_EVENT_FLAG_NO_DEFAULT;
 
     // Need to set an extra flag for drag events.
-    if (mEvent->eventStructType == NS_DRAG_EVENT &&
-        NS_IS_TRUSTED_EVENT(mEvent)) {
+    if (mEvent->eventStructType == NS_DRAG_EVENT && mEvent->mFlags.mIsTrusted) {
       nsCOMPtr<nsINode> node = do_QueryInterface(mEvent->currentTarget);
       if (!node) {
         nsCOMPtr<nsPIDOMWindow> win = do_QueryInterface(mEvent->currentTarget);
@@ -470,7 +463,7 @@ nsDOMEvent::InitEvent(const nsAString& aEventTypeArg, bool aCanBubbleArg, bool a
   // Make sure this event isn't already being dispatched.
   NS_ENSURE_TRUE(!NS_IS_EVENT_IN_DISPATCH(mEvent), NS_OK);
 
-  if (NS_IS_TRUSTED_EVENT(mEvent)) {
+  if (mEvent->mFlags.mIsTrusted) {
     // Ensure the caller is permitted to dispatch trusted DOM events.
     if (!nsContentUtils::IsCallerChrome()) {
       SetTrusted(false);
@@ -798,6 +791,7 @@ nsDOMEvent::DuplicatePrivateData()
   newEvent->currentTarget          = mEvent->currentTarget;
   newEvent->originalTarget         = mEvent->originalTarget;
   newEvent->flags                  = mEvent->flags;
+  newEvent->mFlags                 = mEvent->mFlags;
   newEvent->time                   = mEvent->time;
   newEvent->refPoint               = mEvent->refPoint;
   newEvent->userType               = mEvent->userType;
@@ -934,7 +928,7 @@ nsDOMEvent::GetEventPopupControlState(nsEvent *aEvent)
     }
     break;
   case NS_KEY_EVENT :
-    if (NS_IS_TRUSTED_EVENT(aEvent)) {
+    if (aEvent->mFlags.mIsTrusted) {
       uint32_t key = static_cast<nsKeyEvent *>(aEvent)->keyCode;
       switch(aEvent->message) {
       case NS_KEY_PRESS :
@@ -959,7 +953,7 @@ nsDOMEvent::GetEventPopupControlState(nsEvent *aEvent)
     }
     break;
   case NS_MOUSE_EVENT :
-    if (NS_IS_TRUSTED_EVENT(aEvent) &&
+    if (aEvent->mFlags.mIsTrusted &&
         static_cast<nsMouseEvent*>(aEvent)->button == nsMouseEvent::eLeftButton) {
       switch(aEvent->message) {
       case NS_MOUSE_BUTTON_UP :
diff --git a/content/events/src/nsEventListenerManager.cpp b/content/events/src/nsEventListenerManager.cpp
index 765d3703b245..4dc2ca0b7f5f 100644
--- a/content/events/src/nsEventListenerManager.cpp
+++ b/content/events/src/nsEventListenerManager.cpp
@@ -958,7 +958,7 @@ nsEventListenerManager::HandleEventInternal(nsPresContext* aPresContext,
       if ((ls->mFlags & aFlags & ~NS_EVENT_FLAG_SYSTEM_EVENT) &&
           (ls->mFlags & NS_EVENT_FLAG_SYSTEM_EVENT) ==
           (aFlags & NS_EVENT_FLAG_SYSTEM_EVENT) &&
-          (NS_IS_TRUSTED_EVENT(aEvent) ||
+          (aEvent->mFlags.mIsTrusted ||
            ls->mFlags & NS_PRIV_EVENT_UNTRUSTED_PERMITTED)) {
         if (!*aDOMEvent) {
           nsEventDispatcher::CreateEvent(aPresContext, aEvent,
diff --git a/content/events/src/nsEventStateManager.cpp b/content/events/src/nsEventStateManager.cpp
index b35301dfe0a2..682667535c2b 100644
--- a/content/events/src/nsEventStateManager.cpp
+++ b/content/events/src/nsEventStateManager.cpp
@@ -957,7 +957,7 @@ nsEventStateManager::PreHandleEvent(nsPresContext* aPresContext,
 #endif
   // Store last known screenPoint and clientPoint so pointer lock
   // can use these values as constants.
-  if (NS_IS_TRUSTED_EVENT(aEvent) &&
+  if (aEvent->mFlags.mIsTrusted &&
       ((NS_IS_MOUSE_EVENT_STRUCT(aEvent) &&
        IsMouseEventReal(aEvent)) ||
        aEvent->eventStructType == NS_WHEEL_EVENT)) {
@@ -969,7 +969,7 @@ nsEventStateManager::PreHandleEvent(nsPresContext* aPresContext,
 
   // Do not take account NS_MOUSE_ENTER/EXIT so that loading a page
   // when user is not active doesn't change the state to active.
-  if (NS_IS_TRUSTED_EVENT(aEvent) &&
+  if (aEvent->mFlags.mIsTrusted &&
       ((aEvent->eventStructType == NS_MOUSE_EVENT  &&
         IsMouseEventReal(aEvent) &&
         aEvent->message != NS_MOUSE_ENTER &&
@@ -1117,7 +1117,7 @@ nsEventStateManager::PreHandleEvent(nsPresContext* aPresContext,
     break;
   case NS_WHEEL_WHEEL:
     {
-      NS_ASSERTION(NS_IS_TRUSTED_EVENT(aEvent),
+      NS_ASSERTION(aEvent->mFlags.mIsTrusted,
                    "Untrusted wheel event shouldn't be here");
 
       nsIContent* content = GetFocusedContent();
@@ -1243,7 +1243,7 @@ nsEventStateManager::PreHandleEvent(nsPresContext* aPresContext,
     }
     break;
   case NS_COMPOSITION_START:
-    if (NS_IS_TRUSTED_EVENT(aEvent)) {
+    if (aEvent->mFlags.mIsTrusted) {
       // If the event is trusted event, set the selected text to data of
       // composition event.
       nsCompositionEvent *compositionEvent =
@@ -1437,10 +1437,9 @@ nsEventStateManager::HandleAccessKey(nsPresContext* aPresContext,
   if (mAccessKeys.Count() > 0 &&
       aModifierMask == GetAccessModifierMask(pcContainer)) {
     // Someone registered an accesskey.  Find and activate it.
-    bool isTrusted = NS_IS_TRUSTED_EVENT(aEvent);
     nsAutoTArray<uint32_t, 10> accessCharCodes;
     nsContentUtils::GetAccessKeyCandidates(aEvent, accessCharCodes);
-    if (ExecuteAccessKey(accessCharCodes, isTrusted)) {
+    if (ExecuteAccessKey(accessCharCodes, aEvent->mFlags.mIsTrusted)) {
       *aStatus = nsEventStatus_eConsumeNoDefault;
       return;
     }
@@ -1752,7 +1751,7 @@ nsEventStateManager::CreateClickHoldTimer(nsPresContext* inPresContext,
                                           nsIFrame* inDownFrame,
                                           nsGUIEvent* inMouseDownEvent)
 {
-  if (!NS_IS_TRUSTED_EVENT(inMouseDownEvent))
+  if (!inMouseDownEvent->mFlags.mIsTrusted)
     return;
 
   // just to be anal (er, safe)
@@ -2105,10 +2104,12 @@ nsEventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
       nsCOMPtr<nsIWidget> widget = mCurrentTarget->GetNearestWidget();
 
       // get the widget from the target frame
-      nsDragEvent startEvent(NS_IS_TRUSTED_EVENT(aEvent), NS_DRAGDROP_START, widget);
+      nsDragEvent startEvent(aEvent->mFlags.mIsTrusted,
+                             NS_DRAGDROP_START, widget);
       FillInEventFromGestureDown(&startEvent);
 
-      nsDragEvent gestureEvent(NS_IS_TRUSTED_EVENT(aEvent), NS_DRAGDROP_GESTURE, widget);
+      nsDragEvent gestureEvent(aEvent->mFlags.mIsTrusted,
+                               NS_DRAGDROP_GESTURE, widget);
       FillInEventFromGestureDown(&gestureEvent);
 
       startEvent.dataTransfer = gestureEvent.dataTransfer = dataTransfer;
@@ -2654,7 +2655,7 @@ nsEventStateManager::SendLineScrollEvent(nsIFrame* aTargetFrame,
     targetContent = targetContent->GetParent();
   }
 
-  nsMouseScrollEvent event(NS_IS_TRUSTED_EVENT(aEvent), NS_MOUSE_SCROLL,
+  nsMouseScrollEvent event(aEvent->mFlags.mIsTrusted, NS_MOUSE_SCROLL,
                            aEvent->widget);
   if (*aStatus == nsEventStatus_eConsumeNoDefault) {
     event.flags |= NS_EVENT_FLAG_NO_DEFAULT;
@@ -2690,7 +2691,7 @@ nsEventStateManager::SendPixelScrollEvent(nsIFrame* aTargetFrame,
     targetContent = targetContent->GetParent();
   }
 
-  nsMouseScrollEvent event(NS_IS_TRUSTED_EVENT(aEvent), NS_MOUSE_PIXEL_SCROLL,
+  nsMouseScrollEvent event(aEvent->mFlags.mIsTrusted, NS_MOUSE_PIXEL_SCROLL,
                            aEvent->widget);
   if (*aStatus == nsEventStatus_eConsumeNoDefault) {
     event.flags |= NS_EVENT_FLAG_NO_DEFAULT;
@@ -3307,7 +3308,7 @@ nsEventStateManager::PostHandleEvent(nsPresContext* aPresContext,
     break;
   case NS_WHEEL_WHEEL:
     {
-      MOZ_ASSERT(NS_IS_TRUSTED_EVENT(aEvent));
+      MOZ_ASSERT(aEvent->mFlags.mIsTrusted);
 
       if (*aStatus == nsEventStatus_eConsumeNoDefault) {
         break;
@@ -3471,7 +3472,8 @@ nsEventStateManager::PostHandleEvent(nsPresContext* aPresContext,
                                            getter_AddRefs(targetContent));
 
         nsCOMPtr<nsIWidget> widget = mCurrentTarget->GetNearestWidget();
-        nsDragEvent event(NS_IS_TRUSTED_EVENT(aEvent), NS_DRAGDROP_DRAGDROP, widget);
+        nsDragEvent event(aEvent->mFlags.mIsTrusted,
+                          NS_DRAGDROP_DRAGDROP, widget);
 
         nsMouseEvent* mouseEvent = static_cast<nsMouseEvent*>(aEvent);
         event.refPoint = mouseEvent->refPoint;
@@ -3906,7 +3908,7 @@ nsEventStateManager::DispatchMouseEvent(nsGUIEvent* aEvent, uint32_t aMessage,
 
   SAMPLE_LABEL("Input", "DispatchMouseEvent");
   nsEventStatus status = nsEventStatus_eIgnore;
-  nsMouseEvent event(NS_IS_TRUSTED_EVENT(aEvent), aMessage, aEvent->widget,
+  nsMouseEvent event(aEvent->mFlags.mIsTrusted, aMessage, aEvent->widget,
                      nsMouseEvent::eReal);
   event.refPoint = aEvent->refPoint;
   event.modifiers = ((nsMouseEvent*)aEvent)->modifiers;
@@ -4368,7 +4370,7 @@ nsEventStateManager::FireDragEnterOrExit(nsPresContext* aPresContext,
                                          nsWeakFrame& aTargetFrame)
 {
   nsEventStatus status = nsEventStatus_eIgnore;
-  nsDragEvent event(NS_IS_TRUSTED_EVENT(aEvent), aMsg, aEvent->widget);
+  nsDragEvent event(aEvent->mFlags.mIsTrusted, aMsg, aEvent->widget);
   event.refPoint = aEvent->refPoint;
   event.modifiers = ((nsMouseEvent*)aEvent)->modifiers;
   event.buttons = ((nsMouseEvent*)aEvent)->buttons;
@@ -4522,8 +4524,8 @@ nsEventStateManager::CheckForAndDispatchClick(nsPresContext* aPresContext,
         sLeftClickOnly ? NS_EVENT_FLAG_NO_CONTENT_DISPATCH : NS_EVENT_FLAG_NONE;
     }
 
-    nsMouseEvent event(NS_IS_TRUSTED_EVENT(aEvent), NS_MOUSE_CLICK, aEvent->widget,
-                       nsMouseEvent::eReal);
+    nsMouseEvent event(aEvent->mFlags.mIsTrusted, NS_MOUSE_CLICK,
+                       aEvent->widget, nsMouseEvent::eReal);
     event.refPoint = aEvent->refPoint;
     event.clickCount = aEvent->clickCount;
     event.modifiers = aEvent->modifiers;
@@ -4541,7 +4543,7 @@ nsEventStateManager::CheckForAndDispatchClick(nsPresContext* aPresContext,
                                              mouseContent, aStatus);
       if (NS_SUCCEEDED(ret) && aEvent->clickCount == 2) {
         //fire double click
-        nsMouseEvent event2(NS_IS_TRUSTED_EVENT(aEvent), NS_MOUSE_DOUBLECLICK,
+        nsMouseEvent event2(aEvent->mFlags.mIsTrusted, NS_MOUSE_DOUBLECLICK,
                             aEvent->widget, nsMouseEvent::eReal);
         event2.refPoint = aEvent->refPoint;
         event2.clickCount = aEvent->clickCount;
diff --git a/content/events/src/nsEventStateManager.h b/content/events/src/nsEventStateManager.h
index 0ce6a01bf7ca..642d8e99d7a1 100644
--- a/content/events/src/nsEventStateManager.h
+++ b/content/events/src/nsEventStateManager.h
@@ -822,7 +822,7 @@ public:
       if (mIsMouseDown) {
         nsIPresShell::SetCapturingContent(nullptr, 0);
         nsIPresShell::AllowMouseCapture(true);
-        if (aDocument && NS_IS_TRUSTED_EVENT(aEvent)) {
+        if (aDocument && aEvent->mFlags.mIsTrusted) {
           nsFocusManager* fm = nsFocusManager::GetFocusManager();
           if (fm) {
             fm->SetMouseButtonDownHandlingDocument(aDocument);
diff --git a/content/events/src/nsIMEStateManager.cpp b/content/events/src/nsIMEStateManager.cpp
index 985900286749..8174e704f5ce 100644
--- a/content/events/src/nsIMEStateManager.cpp
+++ b/content/events/src/nsIMEStateManager.cpp
@@ -549,7 +549,7 @@ nsIMEStateManager::DispatchCompositionEvent(nsINode* aEventTargetNode,
 {
   MOZ_ASSERT(aEvent->eventStructType == NS_COMPOSITION_EVENT ||
              aEvent->eventStructType == NS_TEXT_EVENT);
-  if (!NS_IS_TRUSTED_EVENT(aEvent) ||
+  if (!aEvent->mFlags.mIsTrusted ||
       (aEvent->flags & NS_EVENT_FLAG_STOP_DISPATCH) != 0) {
     return;
   }
diff --git a/content/html/content/src/nsGenericHTMLElement.cpp b/content/html/content/src/nsGenericHTMLElement.cpp
index fd349a83e7f2..b10f31fd930a 100644
--- a/content/html/content/src/nsGenericHTMLElement.cpp
+++ b/content/html/content/src/nsGenericHTMLElement.cpp
@@ -3336,7 +3336,7 @@ nsGenericHTMLFormElement::AfterSetAttr(int32_t aNameSpaceID, nsIAtom* aName,
 nsresult
 nsGenericHTMLFormElement::PreHandleEvent(nsEventChainPreVisitor& aVisitor)
 {
-  if (NS_IS_TRUSTED_EVENT(aVisitor.mEvent)) {
+  if (aVisitor.mEvent->mFlags.mIsTrusted) {
     switch (aVisitor.mEvent->message) {
       case NS_FOCUS_CONTENT:
       {
diff --git a/content/html/content/src/nsHTMLButtonElement.cpp b/content/html/content/src/nsHTMLButtonElement.cpp
index 3cbbb9d0b3ff..87692992ba16 100644
--- a/content/html/content/src/nsHTMLButtonElement.cpp
+++ b/content/html/content/src/nsHTMLButtonElement.cpp
@@ -298,7 +298,7 @@ nsHTMLButtonElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
 
   if (aVisitor.mEventStatus != nsEventStatus_eConsumeNoDefault &&
       NS_IS_MOUSE_LEFT_CLICK(aVisitor.mEvent)) {
-    nsUIEvent actEvent(NS_IS_TRUSTED_EVENT(aVisitor.mEvent), NS_UI_ACTIVATE, 1);
+    nsUIEvent actEvent(aVisitor.mEvent->mFlags.mIsTrusted, NS_UI_ACTIVATE, 1);
 
     nsCOMPtr<nsIPresShell> shell = aVisitor.mPresContext->GetPresShell();
     if (shell) {
@@ -337,7 +337,7 @@ nsHTMLButtonElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
                NS_KEY_UP == aVisitor.mEvent->message)) {
             nsEventStatus status = nsEventStatus_eIgnore;
 
-            nsMouseEvent event(NS_IS_TRUSTED_EVENT(aVisitor.mEvent),
+            nsMouseEvent event(aVisitor.mEvent->mFlags.mIsTrusted,
                                NS_MOUSE_CLICK, nullptr,
                                nsMouseEvent::eReal);
             event.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_KEYBOARD;
@@ -354,7 +354,7 @@ nsHTMLButtonElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
           if (aVisitor.mEvent->eventStructType == NS_MOUSE_EVENT) {
             if (static_cast<nsMouseEvent*>(aVisitor.mEvent)->button ==
                   nsMouseEvent::eLeftButton) {
-              if (NS_IS_TRUSTED_EVENT(aVisitor.mEvent)) {
+              if (aVisitor.mEvent->mFlags.mIsTrusted) {
                 nsEventStateManager* esm =
                   aVisitor.mPresContext->EventStateManager();
                 nsEventStateManager::SetActiveManager(
diff --git a/content/html/content/src/nsHTMLInputElement.cpp b/content/html/content/src/nsHTMLInputElement.cpp
index 29fdcc104834..fecb74d76ecd 100644
--- a/content/html/content/src/nsHTMLInputElement.cpp
+++ b/content/html/content/src/nsHTMLInputElement.cpp
@@ -2250,7 +2250,7 @@ nsHTMLInputElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
   if (aVisitor.mEventStatus != nsEventStatus_eConsumeNoDefault &&
       !IsSingleLineTextControl(true) &&
       NS_IS_MOUSE_LEFT_CLICK(aVisitor.mEvent)) {
-    nsUIEvent actEvent(NS_IS_TRUSTED_EVENT(aVisitor.mEvent), NS_UI_ACTIVATE, 1);
+    nsUIEvent actEvent(aVisitor.mEvent->mFlags.mIsTrusted, NS_UI_ACTIVATE, 1);
 
     nsCOMPtr<nsIPresShell> shell = aVisitor.mPresContext->GetPresShell();
     if (shell) {
@@ -2392,7 +2392,7 @@ nsHTMLInputElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
               case NS_FORM_INPUT_SUBMIT:
               case NS_FORM_INPUT_IMAGE: // Bug 34418
               {
-                nsMouseEvent event(NS_IS_TRUSTED_EVENT(aVisitor.mEvent),
+                nsMouseEvent event(aVisitor.mEvent->mFlags.mIsTrusted,
                                    NS_MOUSE_CLICK, nullptr, nsMouseEvent::eReal);
                 event.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_KEYBOARD;
                 nsEventStatus status = nsEventStatus_eIgnore;
@@ -2429,7 +2429,7 @@ nsHTMLInputElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
                   rv = selectedRadioButton->Focus();
                   if (NS_SUCCEEDED(rv)) {
                     nsEventStatus status = nsEventStatus_eIgnore;
-                    nsMouseEvent event(NS_IS_TRUSTED_EVENT(aVisitor.mEvent),
+                    nsMouseEvent event(aVisitor.mEvent->mFlags.mIsTrusted,
                                        NS_MOUSE_CLICK, nullptr,
                                        nsMouseEvent::eReal);
                     event.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_KEYBOARD;
diff --git a/content/xul/content/src/nsXULElement.cpp b/content/xul/content/src/nsXULElement.cpp
index d8c1816131eb..cf5cad38e23f 100644
--- a/content/xul/content/src/nsXULElement.cpp
+++ b/content/xul/content/src/nsXULElement.cpp
@@ -1155,7 +1155,7 @@ nsXULElement::PreHandleEvent(nsEventChainPreVisitor& aVisitor)
                     static_cast<nsInputEvent*>(aVisitor.mEvent);
                 nsContentUtils::DispatchXULCommand(
                   commandContent,
-                  NS_IS_TRUSTED_EVENT(aVisitor.mEvent),
+                  aVisitor.mEvent->mFlags.mIsTrusted,
                   aVisitor.mDOMEvent,
                   nullptr,
                   orig->IsControl(),
diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 676ffa7d9ee3..3e20f260e740 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -2464,11 +2464,11 @@ nsGlobalWindow::PreHandleEvent(nsEventChainPreVisitor& aVisitor)
   } else if (msg == NS_RESIZE_EVENT) {
     mIsHandlingResizeEvent = true;
   } else if (msg == NS_MOUSE_BUTTON_DOWN &&
-             NS_IS_TRUSTED_EVENT(aVisitor.mEvent)) {
+             aVisitor.mEvent->mFlags.mIsTrusted) {
     gMouseDown = true;
   } else if ((msg == NS_MOUSE_BUTTON_UP ||
               msg == NS_DRAGDROP_END) &&
-             NS_IS_TRUSTED_EVENT(aVisitor.mEvent)) {
+             aVisitor.mEvent->mFlags.mIsTrusted) {
     gMouseDown = false;
     if (gDragServiceDisabled) {
       nsCOMPtr<nsIDragService> ds =
@@ -2484,7 +2484,7 @@ nsGlobalWindow::PreHandleEvent(nsEventChainPreVisitor& aVisitor)
 
   // Handle 'active' event.
   if (!mIdleObservers.IsEmpty() &&
-      NS_IS_TRUSTED_EVENT(aVisitor.mEvent) &&
+      aVisitor.mEvent->mFlags.mIsTrusted &&
       (NS_IS_MOUSE_EVENT(aVisitor.mEvent) ||
        NS_IS_DRAG_EVENT(aVisitor.mEvent))) {
     mAddActiveEventFuzzTime = false;
@@ -2633,7 +2633,7 @@ nsGlobalWindow::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
   if (aVisitor.mEvent->message == NS_RESIZE_EVENT) {
     mIsHandlingResizeEvent = false;
   } else if (aVisitor.mEvent->message == NS_PAGE_UNLOAD &&
-             NS_IS_TRUSTED_EVENT(aVisitor.mEvent)) {
+             aVisitor.mEvent->mFlags.mIsTrusted) {
     // Execute bindingdetached handlers before we tear ourselves
     // down.
     if (mDocument) {
@@ -2642,7 +2642,7 @@ nsGlobalWindow::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
     }
     mIsDocumentLoaded = false;
   } else if (aVisitor.mEvent->message == NS_LOAD &&
-             NS_IS_TRUSTED_EVENT(aVisitor.mEvent)) {
+             aVisitor.mEvent->mFlags.mIsTrusted) {
     // This is page load event since load events don't propagate to |window|.
     // @see nsDocument::PreHandleEvent.
     mIsDocumentLoaded = true;
@@ -2663,7 +2663,7 @@ nsGlobalWindow::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
       // onload event for the frame element.
 
       nsEventStatus status = nsEventStatus_eIgnore;
-      nsEvent event(NS_IS_TRUSTED_EVENT(aVisitor.mEvent), NS_LOAD);
+      nsEvent event(aVisitor.mEvent->mFlags.mIsTrusted, NS_LOAD);
       event.flags |= NS_EVENT_FLAG_CANT_BUBBLE;
 
       // Most of the time we could get a pres context to pass in here,
diff --git a/dom/plugins/base/nsPluginInstanceOwner.cpp b/dom/plugins/base/nsPluginInstanceOwner.cpp
index 9715ef27fcfd..e54965484c99 100644
--- a/dom/plugins/base/nsPluginInstanceOwner.cpp
+++ b/dom/plugins/base/nsPluginInstanceOwner.cpp
@@ -1828,7 +1828,7 @@ nsresult nsPluginInstanceOwner::DispatchFocusToPlugin(nsIDOMEvent* aFocusEvent)
   nsEvent* theEvent = aFocusEvent->GetInternalNSEvent();
   if (theEvent) {
     // we only care about the message in ProcessEvent
-    nsGUIEvent focusEvent(NS_IS_TRUSTED_EVENT(theEvent), theEvent->message,
+    nsGUIEvent focusEvent(theEvent->mFlags.mIsTrusted, theEvent->message,
                           nullptr);
     nsEventStatus rv = ProcessEvent(focusEvent);
     if (nsEventStatus_eConsumeNoDefault == rv) {
@@ -2002,7 +2002,7 @@ nsPluginInstanceOwner::HandleEvent(nsIDOMEvent* aEvent)
   nsCOMPtr<nsIDOMDragEvent> dragEvent(do_QueryInterface(aEvent));
   if (dragEvent && mInstance) {
     nsEvent* ievent = aEvent->GetInternalNSEvent();
-    if ((ievent && NS_IS_TRUSTED_EVENT(ievent)) &&
+    if ((ievent && ievent->mFlags.mIsTrusted) &&
          ievent->message != NS_DRAGDROP_ENTER && ievent->message != NS_DRAGDROP_OVER) {
       aEvent->PreventDefault();
     }
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index ba09f985ecfc..093d0d756583 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -6371,7 +6371,7 @@ PresShell::HandleEventInternal(nsEvent* aEvent, nsEventStatus* aStatus)
     bool isHandlingUserInput = false;
 
     // XXX How about IME events and input events for plugins?
-    if (NS_IS_TRUSTED_EVENT(aEvent)) {
+    if (aEvent->mFlags.mIsTrusted) {
       switch (aEvent->message) {
       case NS_KEY_PRESS:
       case NS_KEY_DOWN:
@@ -6517,7 +6517,7 @@ PresShell::HandleEventInternal(nsEvent* aEvent, nsEventStatus* aStatus)
     nsAutoHandlingUserInputStatePusher userInpStatePusher(isHandlingUserInput,
                                                           aEvent, mDocument);
 
-    if (NS_IS_TRUSTED_EVENT(aEvent) && aEvent->message == NS_MOUSE_MOVE) {
+    if (aEvent->mFlags.mIsTrusted && aEvent->message == NS_MOUSE_MOVE) {
       nsIPresShell::AllowMouseCapture(
         nsEventStateManager::GetActiveEventStateManager() == manager);
     }
@@ -6660,9 +6660,7 @@ PresShell::DispatchTouchEvent(nsEvent *aEvent,
       content = capturingContent;
     }
     // copy the event
-    nsTouchEvent newEvent(NS_IS_TRUSTED_EVENT(touchEvent) ?
-                            true : false,
-                          touchEvent);
+    nsTouchEvent newEvent(touchEvent->mFlags.mIsTrusted, touchEvent);
     newEvent.target = targetPtr;
 
     nsRefPtr<PresShell> contentPresShell;
diff --git a/layout/base/nsPresShell.h b/layout/base/nsPresShell.h
index 1927b303e7a4..04a315c19830 100644
--- a/layout/base/nsPresShell.h
+++ b/layout/base/nsPresShell.h
@@ -560,7 +560,7 @@ protected:
   public:
     nsDelayedMouseEvent(nsMouseEvent* aEvent) : nsDelayedInputEvent()
     {
-      mEvent = new nsMouseEvent(NS_IS_TRUSTED_EVENT(aEvent),
+      mEvent = new nsMouseEvent(aEvent->mFlags.mIsTrusted,
                                 aEvent->message,
                                 aEvent->widget,
                                 aEvent->reason,
@@ -580,7 +580,7 @@ protected:
   public:
     nsDelayedKeyEvent(nsKeyEvent* aEvent) : nsDelayedInputEvent()
     {
-      mEvent = new nsKeyEvent(NS_IS_TRUSTED_EVENT(aEvent),
+      mEvent = new nsKeyEvent(aEvent->mFlags.mIsTrusted,
                               aEvent->message,
                               aEvent->widget);
       Init(aEvent);
diff --git a/layout/xul/base/src/nsButtonBoxFrame.cpp b/layout/xul/base/src/nsButtonBoxFrame.cpp
index 7312233f2a92..4b3a5bddc50d 100644
--- a/layout/xul/base/src/nsButtonBoxFrame.cpp
+++ b/layout/xul/base/src/nsButtonBoxFrame.cpp
@@ -136,7 +136,7 @@ nsButtonBoxFrame::DoMouseClick(nsGUIEvent* aEvent, bool aTrustEvent)
   if (shell) {
     nsContentUtils::DispatchXULCommand(mContent,
                                        aEvent ?
-                                         NS_IS_TRUSTED_EVENT(aEvent) : aTrustEvent,
+                                         aEvent->mFlags.mIsTrusted : aTrustEvent,
                                        nullptr, shell,
                                        isControl, isAlt, isShift, isMeta);
   }
diff --git a/layout/xul/base/src/nsMenuFrame.cpp b/layout/xul/base/src/nsMenuFrame.cpp
index d10bf602fdba..8fb3b68320a0 100644
--- a/layout/xul/base/src/nsMenuFrame.cpp
+++ b/layout/xul/base/src/nsMenuFrame.cpp
@@ -1226,7 +1226,7 @@ nsMenuFrame::CreateMenuCommandEvent(nsGUIEvent *aEvent, bool aFlipChecked)
   // Create a trusted event if the triggering event was trusted, or if
   // we're called from chrome code (since at least one of our caller
   // passes in a null event).
-  bool isTrusted = aEvent ? NS_IS_TRUSTED_EVENT(aEvent) :
+  bool isTrusted = aEvent ? aEvent->mFlags.mIsTrusted :
                               nsContentUtils::IsCallerChrome();
 
   bool shift = false, control = false, alt = false, meta = false;
diff --git a/layout/xul/base/src/nsResizerFrame.cpp b/layout/xul/base/src/nsResizerFrame.cpp
index ed9cc675c65d..87edc8099608 100644
--- a/layout/xul/base/src/nsResizerFrame.cpp
+++ b/layout/xul/base/src/nsResizerFrame.cpp
@@ -545,6 +545,5 @@ nsResizerFrame::MouseClicked(nsPresContext* aPresContext, nsGUIEvent *aEvent)
 {
   // Execute the oncommand event handler.
   nsContentUtils::DispatchXULCommand(mContent,
-                                     aEvent ?
-                                       NS_IS_TRUSTED_EVENT(aEvent) : false);
+                                     aEvent && aEvent->mFlags.mIsTrusted);
 }
diff --git a/layout/xul/base/src/nsScrollBoxFrame.cpp b/layout/xul/base/src/nsScrollBoxFrame.cpp
index b66753079bce..83857afb18bf 100644
--- a/layout/xul/base/src/nsScrollBoxFrame.cpp
+++ b/layout/xul/base/src/nsScrollBoxFrame.cpp
@@ -89,7 +89,7 @@ nsAutoRepeatBoxFrame::HandleEvent(nsPresContext* aPresContext,
     case NS_MOUSE_ENTER_SYNTH:
       if (IsActivatedOnHover()) {
         StartRepeat();
-        mTrustedEvent = NS_IS_TRUSTED_EVENT(aEvent);
+        mTrustedEvent = aEvent->mFlags.mIsTrusted;
       }
       break;
 
@@ -119,7 +119,7 @@ nsAutoRepeatBoxFrame::HandlePress(nsPresContext* aPresContext,
 {
   if (!IsActivatedOnHover()) {
     StartRepeat();
-    mTrustedEvent = NS_IS_TRUSTED_EVENT(aEvent);
+    mTrustedEvent = aEvent->mFlags.mIsTrusted;
     DoMouseClick(aEvent, mTrustedEvent);
   }
 
diff --git a/layout/xul/base/src/nsTitleBarFrame.cpp b/layout/xul/base/src/nsTitleBarFrame.cpp
index a7d5abf86fd4..d640bb7f5fd6 100644
--- a/layout/xul/base/src/nsTitleBarFrame.cpp
+++ b/layout/xul/base/src/nsTitleBarFrame.cpp
@@ -172,6 +172,5 @@ nsTitleBarFrame::MouseClicked(nsPresContext* aPresContext, nsGUIEvent* aEvent)
 {
   // Execute the oncommand event handler.
   nsContentUtils::DispatchXULCommand(mContent,
-                                     aEvent ?
-                                       NS_IS_TRUSTED_EVENT(aEvent) : false);
+                                     aEvent && aEvent->mFlags.mIsTrusted);
 }
diff --git a/widget/nsEvent.h b/widget/nsEvent.h
index 390a45cb22d5..ad818c3188f7 100644
--- a/widget/nsEvent.h
+++ b/widget/nsEvent.h
@@ -78,6 +78,8 @@ class nsPluginEvent;
 namespace mozilla {
 namespace widget {
 
+struct EventFlags;
+
 class WheelEvent;
 
 // All modifier keys should be defined here.  This is used for managing
diff --git a/widget/nsGUIEvent.h b/widget/nsGUIEvent.h
index a2ea2642004b..8ad1b3798bff 100644
--- a/widget/nsGUIEvent.h
+++ b/widget/nsGUIEvent.h
@@ -109,7 +109,6 @@ enum nsEventStructType {
 // listener flags and event flags, but only some of them. You've been
 // warned!
 #define NS_EVENT_FLAG_NONE                0x0000
-#define NS_EVENT_FLAG_TRUSTED             0x0001
 #define NS_EVENT_FLAG_BUBBLE              0x0002
 #define NS_EVENT_FLAG_CAPTURE             0x0004
 #define NS_EVENT_FLAG_STOP_DISPATCH       0x0008
@@ -510,6 +509,50 @@ enum nsWindowZ {
   nsWindowZRelative   // just below some specified widget
 };
 
+namespace mozilla {
+namespace widget {
+struct EventFlags
+{
+public:
+  // If mIsTrusted is true, the event is a trusted event.  Otherwise, it's
+  // an untrusted event.
+  bool    mIsTrusted : 1;
+
+  EventFlags()
+  {
+    Clear();
+  }
+  inline void Clear()
+  {
+    SetRawFlags(0);
+  }
+  inline EventFlags operator|(const EventFlags& aOther) const
+  {
+    EventFlags flags;
+    flags.SetRawFlags(GetRawFlags() | aOther.GetRawFlags());
+    return flags;
+  }
+  inline EventFlags& operator|=(const EventFlags& aOther)
+  {
+    SetRawFlags(GetRawFlags() | aOther.GetRawFlags());
+    return *this;
+  }
+
+private:
+  inline void SetRawFlags(uint32_t aRawFlags)
+  {
+    memcpy(this, &aRawFlags, sizeof(EventFlags));
+  }
+  inline uint32_t GetRawFlags() const
+  {
+    uint32_t result = 0;
+    memcpy(&result, this, sizeof(EventFlags));
+    return result;
+  }
+};
+} // namespace widget
+} // namespace mozilla
+
 /**
  * General event
  */
@@ -523,10 +566,11 @@ protected:
       refPoint(0, 0),
       lastRefPoint(0, 0),
       time(0),
-      flags(isTrusted ? NS_EVENT_FLAG_TRUSTED : NS_EVENT_FLAG_NONE),
+      flags(NS_EVENT_FLAG_NONE),
       userType(0)
   {
     MOZ_COUNT_CTOR(nsEvent);
+    mFlags.mIsTrusted = isTrusted;
   }
 
   nsEvent()
@@ -541,10 +585,11 @@ public:
       refPoint(0, 0),
       lastRefPoint(0, 0),
       time(0),
-      flags(isTrusted ? NS_EVENT_FLAG_TRUSTED : NS_EVENT_FLAG_NONE),
+      flags(NS_EVENT_FLAG_NONE),
       userType(0)
   {
     MOZ_COUNT_CTOR(nsEvent);
+    mFlags.mIsTrusted = isTrusted;
   }
 
   ~nsEvent()
@@ -573,6 +618,10 @@ public:
   // Flags to hold event flow stage and capture/bubble cancellation
   // status. This is used also to indicate whether the event is trusted.
   uint32_t    flags;
+
+  // See EventFlags definition for the detail.
+  mozilla::widget::EventFlags mFlags;
+
   // Additional type info for user defined events
   nsCOMPtr<nsIAtom>     userType;
   // Event targets, needed by DOM Events
@@ -1592,7 +1641,7 @@ public:
   }
 
   nsSimpleGestureEvent(const nsSimpleGestureEvent& other)
-    : nsMouseEvent_base((other.flags & NS_EVENT_FLAG_TRUSTED) != 0,
+    : nsMouseEvent_base(other.mFlags.mIsTrusted,
                         other.message, other.widget, NS_SIMPLE_GESTURE_EVENT),
       direction(other.direction), delta(other.delta), clickCount(0)
   {
@@ -1747,9 +1796,6 @@ enum nsDragDropEventStatus {
        (NS_IS_PLUGIN_EVENT(evnt) && \
         !(static_cast<nsPluginEvent*>(evnt)->retargetToFocusedDocument))
 
-#define NS_IS_TRUSTED_EVENT(event) \
-  (((event)->flags & NS_EVENT_FLAG_TRUSTED) != 0)
-
 // Mark an event as being dispatching.
 #define NS_MARK_EVENT_DISPATCH_STARTED(event) \
   (event)->flags |= NS_EVENT_FLAG_DISPATCHING;
diff --git a/widget/nsGUIEventIPC.h b/widget/nsGUIEventIPC.h
index b0087bda6935..a806f0420467 100644
--- a/widget/nsGUIEventIPC.h
+++ b/widget/nsGUIEventIPC.h
@@ -13,6 +13,23 @@
 namespace IPC
 {
 
+template<>
+struct ParamTraits<mozilla::widget::EventFlags>
+{
+  typedef mozilla::widget::EventFlags paramType;
+
+  static void Write(Message* aMsg, const paramType& aParam)
+  {
+    aMsg->WriteBytes(&aParam, sizeof(paramType));
+  }
+
+  static bool Read(const Message* aMsg, void** aIter, paramType* aResult)
+  {
+    return aMsg->ReadBytes(aIter, reinterpret_cast<const char**>(aResult),
+                           sizeof(paramType));
+  }
+};
+
 template<>
 struct ParamTraits<nsEvent>
 {
@@ -25,6 +42,7 @@ struct ParamTraits<nsEvent>
     WriteParam(aMsg, aParam.refPoint);
     WriteParam(aMsg, aParam.time);
     WriteParam(aMsg, aParam.flags);
+    WriteParam(aMsg, aParam.mFlags);
   }
 
   static bool Read(const Message* aMsg, void** aIter, paramType* aResult)
@@ -34,7 +52,8 @@ struct ParamTraits<nsEvent>
                ReadParam(aMsg, aIter, &aResult->message) &&
                ReadParam(aMsg, aIter, &aResult->refPoint) &&
                ReadParam(aMsg, aIter, &aResult->time) &&
-               ReadParam(aMsg, aIter, &aResult->flags);
+               ReadParam(aMsg, aIter, &aResult->flags) &&
+               ReadParam(aMsg, aIter, &aResult->mFlags);
     aResult->eventStructType = static_cast<nsEventStructType>(eventStructType);
     return ret;
   }