ScreenOrientationController: task-based dispatching of change events.

Source/modules/screen_orientation/ScreenOrientationController.cpp

Index: Source/modules/screen_orientation/ScreenOrientationController.cpp
diff --git a/Source/modules/screen_orientation/ScreenOrientationController.cpp b/Source/modules/screen_orientation/ScreenOrientationController.cpp
index 9ea7c471dd53915318dc6d82c784382414c527a7..0d0a0d0396143418cf56f3a977e499a0db74149f 100644
--- a/Source/modules/screen_orientation/ScreenOrientationController.cpp
+++ b/Source/modules/screen_orientation/ScreenOrientationController.cpp
@@ -5,6 +5,8 @@
 #include "config.h"
 #include "modules/screen_orientation/ScreenOrientationController.h"
 
+#include "core/dom/Document.h"
+#include "core/dom/ExecutionContextTask.h"
 #include "core/events/Event.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
@@ -38,7 +40,7 @@ ScreenOrientationController::ScreenOrientationController(LocalFrame& frame, WebS
     : LocalFrameLifecycleObserver(&frame)
     , PlatformEventController(frame.page())
     , m_client(client)
-    , m_dispatchEventTimer(this, &ScreenOrientationController::dispatchEventTimerFired)
+    , m_isDispatchingEvent(false)
 {
 }
 
@@ -135,8 +137,12 @@ void ScreenOrientationController::notifyOrientationChanged()
     }
 
     // Notify current orientation object.
-    if (!m_dispatchEventTimer.isActive())
-        m_dispatchEventTimer.startOneShot(0, FROM_HERE);
+    if (!m_isDispatchingEvent) {
+        if (Document* document = frame()->document()) {
+            document->postTask(FROM_HERE, createSameThreadTask(&ScreenOrientationController::dispatchChangeEvent, this));

[alex clarke (OOO till 29th), 2015/04/15 09:27:32]

FYI the blink scheduler team are thinking of adding a helper to make this kind
of refactor easier.

Something on the lines of helper.postUniqueTask(FROM_HERE,
createSameThreadTask(&ScreenOrientationController::dispatchChangeEvent, this));

The helper would contain the m_isDispatchingEvent logic (since this seems to be
a reasonably common pattern).

The helper's constructor would take the WebThread you wanted the task to run on.

When we implement that, we'll probably refactor this to use the new method. 

+            m_isDispatchingEvent = true;
+        }
+    }
 
     // ... and child frames, if they have a ScreenOrientationController.
     for (size_t i = 0; i < childFrames.size(); ++i) {
@@ -169,8 +175,9 @@ void ScreenOrientationController::unlock()
     m_client->unlockOrientation();
 }
 
-void ScreenOrientationController::dispatchEventTimerFired(Timer<ScreenOrientationController>*)
+void ScreenOrientationController::dispatchChangeEvent()
 {
+    m_isDispatchingEvent = false;
     if (!m_orientation)
         return;
     m_orientation->dispatchEvent(Event::create(EventTypeNames::change));