Bug 1262053 - part1 : unblock window's media when the page was first visited. r=baku

MozReview-Commit-ID: 5g5cYdgC8sg

--HG--
extra : rebase_source : 5af18ff846f464b1d3d195d7dc2634e03601cfcc

dom/base/nsDocument.cpp

@@ -1498,6 +1498,8 @@ nsDocument::nsDocument(const char* aContentType)
     // Add the base queue sentinel to the processing stack.
     sProcessingStack->AppendElement((CustomElementData*) nullptr);
   }
+
+  mEverInForeground = false;
 }
 
 void
@@ -12603,6 +12605,10 @@ nsDocument::UpdateVisibilityState()
 
     EnumerateActivityObservers(NotifyActivityChanged, nullptr);
   }
+
+  if (mVisibilityState == dom::VisibilityState::Visible) {
+    MaybeActiveMediaComponents();
+  }
 }
 
 VisibilityState
@@ -12638,6 +12644,23 @@ nsDocument::PostVisibilityUpdateEvent()
   NS_DispatchToMainThread(event);
 }
 
+void
+nsDocument::MaybeActiveMediaComponents()
+{
+  if (mEverInForeground) {
+    return;
+  }
+
+  if (!mWindow) {
+    return;
+  }
+
+  mEverInForeground = true;
+  if (GetWindow()->GetMediaSuspend() == nsISuspendedTypes::SUSPENDED_BLOCK) {
+    GetWindow()->SetMediaSuspend(nsISuspendedTypes::NONE_SUSPENDED);
+  }
+}
+
 NS_IMETHODIMP
 nsDocument::GetMozHidden(bool* aHidden)
 {

dom/base/nsDocument.h

@@ -1209,6 +1209,10 @@ public:
   // Posts an event to call UpdateVisibilityState
   virtual void PostVisibilityUpdateEvent() override;
 
+  // Since we wouldn't automatically play media from non-visited page, we need
+  // to notify window when the page was first visited.
+  void MaybeActiveMediaComponents();
+
   virtual void DocAddSizeOfExcludingThis(nsWindowSizes* aWindowSizes) const override;
   // DocAddSizeOfIncludingThis is inherited from nsIDocument.
 

dom/base/nsGlobalWindow.cpp

@@ -618,7 +618,8 @@ nsPIDOMWindow<T>::nsPIDOMWindow(nsPIDOMWindowOuter *aOuterWindow)
   mInnerObjectsFreed(false),
   mIsModalContentWindow(false),
   mIsActive(false), mIsBackground(false),
-  mMediaSuspend(nsISuspendedTypes::NONE_SUSPENDED),
+  mMediaSuspend(Preferences::GetBool("media.block-autoplay-until-in-foreground", true) ?
+    nsISuspendedTypes::SUSPENDED_BLOCK : nsISuspendedTypes::NONE_SUSPENDED),
   mAudioMuted(false), mAudioVolume(1.0), mAudioCaptured(false),
   mDesktopModeViewport(false), mInnerWindow(nullptr),
   mOuterWindow(aOuterWindow),

dom/base/nsIDocument.h

@@ -3069,6 +3069,9 @@ protected:
   // Do we currently have an event posted to call FlushUserFontSet?
   bool mPostedFlushUserFontSet : 1;
 
+  // True is document has ever been in a foreground window.
+  bool mEverInForeground : 1;
+
   enum Type {
     eUnknown, // should never be used
     eHTML,

modules/libpref/init/all.js

@@ -5532,6 +5532,7 @@ pref("dom.webkitBlink.dirPicker.enabled", true);
 pref("dom.webkitBlink.filesystem.enabled", true);
 #endif
 
+pref("media.block-autoplay-until-in-foreground", true);
 #ifdef MOZ_STYLO
 // Is the Servo-backed style system enabled?
 pref("layout.css.servo.enabled", true);