Bug 1536353 - part 2: Merge PresShell::EventHandler::PrepareToDispatchEvent() and PresShell::EventHandler::PrepareToDispatchContextMenuEvent() r=smaug

`PresShell::EventHandler::PrepareToDispatchEvent()` checked whether the
given event is a trusted event or an untrusted event, but
`PresShell::EventHandler::PrepareToDispatchOntextMenuEvent()` didn't so.
However, now, both of them don't need to check it.  Therefore, we can merge
them.

Differential Revision: https://phabricator.services.mozilla.com/D24132

--HG--
extra : moz-landing-system : lando

layout/base/PresShell.cpp

@@ -7666,12 +7666,8 @@ nsresult PresShell::EventHandler::HandleEventWithCurrentEventInfo(
     }
   }
 
-  bool isHandlingUserInput = PrepareToDispatchEvent(aEvent);
-
-  // If we cannot open context menu even though eContextMenu is fired, we
-  // should stop dispatching it into the DOM.
-  if (aEvent->mMessage == eContextMenu &&
-      !PrepareToDispatchContextMenuEvent(aEvent)) {
+  bool isHandlingUserInput = false;
+  if (!PrepareToDispatchEvent(aEvent, &isHandlingUserInput)) {
     return NS_OK;
   }
 
@@ -7797,8 +7793,10 @@ nsresult PresShell::EventHandler::DispatchEvent(
       aOverrideClickTarget);
 }
 
-bool PresShell::EventHandler::PrepareToDispatchEvent(WidgetEvent* aEvent) {
+bool PresShell::EventHandler::PrepareToDispatchEvent(WidgetEvent* aEvent,
+                                                     bool* aIsUserInteraction) {
   MOZ_ASSERT(aEvent->IsTrusted());
+  MOZ_ASSERT(aIsUserInteraction);
 
   if (aEvent->IsUserAction()) {
     mPresShell->mHasHandledUserInput = true;
@@ -7813,12 +7811,14 @@ bool PresShell::EventHandler::PrepareToDispatchEvent(WidgetEvent* aEvent) {
       // Not all keyboard events are treated as user input, so that popups
       // can't be opened, fullscreen mode can't be started, etc at unexpected
       // time.
-      return keyboardEvent->CanTreatAsUserInput();
+      *aIsUserInteraction = keyboardEvent->CanTreatAsUserInput();
+      return true;
     }
     case eMouseDown:
     case eMouseUp:
     case ePointerDown:
     case ePointerUp:
+      *aIsUserInteraction = true;
       return true;
 
     case eMouseMove: {
@@ -7827,7 +7827,8 @@ bool PresShell::EventHandler::PrepareToDispatchEvent(WidgetEvent* aEvent) {
                           GetPresContext()->EventStateManager() ==
                               EventStateManager::GetActiveEventStateManager();
       nsIPresShell::AllowMouseCapture(allowCapture);
-      return false;
+      *aIsUserInteraction = false;
+      return true;
     }
     case eDrop: {
       nsCOMPtr<nsIDragSession> session = nsContentUtils::GetDragSession();
@@ -7838,11 +7839,33 @@ bool PresShell::EventHandler::PrepareToDispatchEvent(WidgetEvent* aEvent) {
           aEvent->mFlags.mOnlyChromeDispatch = true;
         }
       }
-      return false;
+      *aIsUserInteraction = false;
+      return true;
     }
+    case eContextMenu: {
+      *aIsUserInteraction = false;
 
+      // If we cannot open context menu even though eContextMenu is fired, we
+      // should stop dispatching it into the DOM.
+      WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+      if (mouseEvent->IsContextMenuKeyEvent() &&
+          !AdjustContextMenuKeyEvent(mouseEvent)) {
+        return false;
+      }
+
+      // If "Shift" state is active, context menu should be forcibly opened even
+      // if web apps want to prevent it since we respect our users' intention.
+      // In this case, we don't fire "contextmenu" event on web content because
+      // of not cancelable.
+      if (mouseEvent->IsShift()) {
+        aEvent->mFlags.mOnlyChromeDispatch = true;
+        aEvent->mFlags.mRetargetToNonNativeAnonymous = true;
+      }
+      return true;
+    }
     default:
-      return false;
+      *aIsUserInteraction = false;
+      return true;
   }
 }
 
@@ -7895,29 +7918,6 @@ void PresShell::EventHandler::FinalizeHandlingEvent(WidgetEvent* aEvent) {
   }
 }
 
-bool PresShell::EventHandler::PrepareToDispatchContextMenuEvent(
-    WidgetEvent* aEvent) {
-  MOZ_ASSERT(aEvent);
-  MOZ_ASSERT(aEvent->mMessage == eContextMenu);
-  MOZ_ASSERT(aEvent->IsTrusted());
-
-  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
-  if (mouseEvent->IsContextMenuKeyEvent() &&
-      !AdjustContextMenuKeyEvent(mouseEvent)) {
-    return false;
-  }
-
-  // If "Shift" state is active, context menu should be forcibly opened even
-  // if web apps want to prevent it since we respect our users' intention.
-  // In this case, we don't fire "contextmenu" event on web content because
-  // of not cancelable.
-  if (mouseEvent->IsShift()) {
-    aEvent->mFlags.mOnlyChromeDispatch = true;
-    aEvent->mFlags.mRetargetToNonNativeAnonymous = true;
-  }
-  return true;
-}
-
 void PresShell::EventHandler::MaybeHandleKeyboardEventBeforeDispatch(
     WidgetKeyboardEvent* aKeyboardEvent) {
   MOZ_ASSERT(aKeyboardEvent);

layout/base/PresShell.h

@@ -1104,13 +1104,16 @@ class PresShell final : public nsIPresShell,
     /**
      * PrepareToDispatchEvent() prepares to dispatch aEvent.
      *
-     * @param aEvent            The handling event.
-     * @return                  true if the event is user interaction.  I.e.,
-     *                          enough obvious input to allow to open popup,
-     *                          etc.  false, otherwise.
+     * @param aEvent                    The handling event.
+     * @param aIsUserInteraction        [out] Set to true if the event is user
+     *                                  interaction.  I.e., enough obvious input
+     *                                  to allow to open popup, etc.  Otherwise,
+     *                                  set to false.
+     * @return                          true if the caller can dispatch the
+     *                                  event into the DOM.
      */
     MOZ_CAN_RUN_SCRIPT
-    bool PrepareToDispatchEvent(WidgetEvent* aEvent);
+    bool PrepareToDispatchEvent(WidgetEvent* aEvent, bool* aIsUserInteraction);
 
     /**
      * MaybeHandleKeyboardEventBeforeDispatch() may handle aKeyboardEvent
@@ -1122,16 +1125,6 @@ class PresShell final : public nsIPresShell,
     void MaybeHandleKeyboardEventBeforeDispatch(
         WidgetKeyboardEvent* aKeyboardEvent);
 
-    /**
-     * PrepareToDispatchContextMenuEvent() prepares to dispatch aEvent into
-     * the DOM.
-     *
-     * @param aEvent            Must be eContextMenu event.
-     * @return                  true if it can be dispatched into the DOM.
-     *                          Otherwise, false.
-     */
-    bool PrepareToDispatchContextMenuEvent(WidgetEvent* aEvent);
-
     /**
      * This and the next two helper methods are used to target and position the
      * context menu when the keyboard shortcut is used to open it.