Bug 1577499 - Part 1: Implement transient activation flag; r=smaug

https://github.com/whatwg/html/pull/3851

Differential Revision: https://phabricator.services.mozilla.com/D44479

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

docshell/base/BrowsingContext.cpp

@@ -384,6 +384,7 @@ void BrowsingContext::PrepareForProcessChange() {
   MOZ_ASSERT(!mIsDiscarded, "We're already closed?");
 
   mIsInProcess = false;
+  mUserGestureStart = TimeStamp();
 
   // NOTE: For now, clear our nsDocShell reference, as we're primarily in a
   // different process now. This may need to change in the future with
@@ -696,14 +697,30 @@ JSObject* BrowsingContext::ReadStructuredClone(JSContext* aCx,
 
 void BrowsingContext::NotifyUserGestureActivation() {
   SetIsActivatedByUserGesture(true);
-
-  // TODO: Bug 1577499 - Implement transient activation flag
 }
 
 void BrowsingContext::NotifyResetUserGestureActivation() {
   SetIsActivatedByUserGesture(false);
+}
 
-  // TODO: Bug 1577499 - Implement transient activation flag
+bool BrowsingContext::HasValidTransientUserGestureActivation() {
+  MOZ_ASSERT(mIsInProcess);
+
+  if (!mIsActivatedByUserGesture) {
+    MOZ_ASSERT(mUserGestureStart.IsNull(),
+               "mUserGestureStart should be null if the document hasn't ever "
+               "been activated by user gesture");
+    return false;
+  }
+
+  MOZ_ASSERT(!mUserGestureStart.IsNull(),
+             "mUserGestureStart shouldn't be null if the document has ever "
+             "been activated by user gesture");
+  TimeDuration timeout = TimeDuration::FromMilliseconds(
+      StaticPrefs::dom_user_activation_transient_timeout());
+
+  return timeout <= TimeDuration() ||
+         (TimeStamp::Now() - mUserGestureStart) <= timeout;
 }
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(BrowsingContext)
@@ -1040,10 +1057,18 @@ void BrowsingContext::StartDelayedAutoplayMediaComponents() {
 }
 
 void BrowsingContext::DidSetIsActivatedByUserGesture() {
+  MOZ_ASSERT_IF(!mIsInProcess, mUserGestureStart.IsNull());
   USER_ACTIVATION_LOG(
       "Set user gesture activation %d for %s browsing context 0x%08" PRIx64,
       mIsActivatedByUserGesture, XRE_IsParentProcess() ? "Parent" : "Child",
       Id());
+  if (mIsInProcess) {
+    USER_ACTIVATION_LOG(
+        "Set user gesture start time for %s browsing context 0x%08" PRIx64,
+        XRE_IsParentProcess() ? "Parent" : "Child", Id());
+    mUserGestureStart =
+        mIsActivatedByUserGesture ? TimeStamp::Now() : TimeStamp();
+  }
 }
 
 void BrowsingContext::DidSetMuted() {

docshell/base/BrowsingContext.h

@@ -279,6 +279,11 @@ class BrowsingContext : public nsWrapperCache, public BrowsingContextBase {
   // activation flag of the top level browsing context.
   void NotifyResetUserGestureActivation();
 
+  // Return true if its corresponding document has transient user gesture
+  // activation and the transient user gesture activation haven't yet timed
+  // out.
+  bool HasValidTransientUserGestureActivation();
+
   // Return the window proxy object that corresponds to this browsing context.
   inline JSObject* GetWindowProxy() const { return mWindowProxy; }
   // Set the window proxy object that corresponds to this browsing context.
@@ -551,6 +556,10 @@ class BrowsingContext : public nsWrapperCache, public BrowsingContextBase {
   // This is true if the BrowsingContext was out of process, but is now in
   // process, and might have remote window proxies that need to be cleaned up.
   bool mDanglingRemoteOuterProxies : 1;
+
+  // The start time of user gesture, this is only available if the browsing
+  // context is in process.
+  TimeStamp mUserGestureStart;
 };
 
 /**

dom/events/EventStateManager.cpp

@@ -818,7 +818,7 @@ void EventStateManager::NotifyTargetUserActivation(WidgetEvent* aEvent,
   }
 
   Document* doc = node->OwnerDoc();
-  if (!doc || doc->HasBeenUserGestureActivated()) {
+  if (!doc) {
     return;
   }
 

modules/libpref/init/StaticPrefList.yaml

@@ -2293,6 +2293,12 @@
   value: false
   mirror: always
 
+# Time limit, in milliseconds, for user gesture transient activation.
+- name: dom.user_activation.transient.timeout
+  type: uint32_t
+  value: 5000
+  mirror: always
+
 # Is support for Window.visualViewport enabled?
 - name: dom.visualviewport.enabled
   type: bool