Unified BeginFrame scheduling

ui/base/android/window_android.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/android/window_android.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
@@ skipping 47 matching lines @@
   if (compositor_ && compositor != compositor_)
     DetachCompositor();
 
   compositor_ = compositor;
   FOR_EACH_OBSERVER(WindowAndroidObserver,
                     observer_list_,
                     OnAttachCompositor());
 }
 
 void WindowAndroid::DetachCompositor() {
-  compositor_ = NULL;
   FOR_EACH_OBSERVER(WindowAndroidObserver,
                     observer_list_,
                     OnDetachCompositor());
+  // Makes |compositor_| NULL after all observers finishes their work.

[brianderson, 2014/09/04 18:45:46]

This comment would be more helpful if it were a "why" instead of a "what".

+  compositor_ = NULL;
   observer_list_.Clear();
 }
 
 void WindowAndroid::RequestVSyncUpdate() {
   JNIEnv* env = AttachCurrentThread();
   Java_WindowAndroid_requestVSyncUpdate(env, GetJavaObject().obj());
 }
 
 void WindowAndroid::SetNeedsAnimate() {
   if (compositor_)
@@ skipping 18 matching lines @@
 // ----------------------------------------------------------------------------
 // Native JNI methods
 // ----------------------------------------------------------------------------
 
 jlong Init(JNIEnv* env, jobject obj, jlong vsync_period) {
   WindowAndroid* window = new WindowAndroid(env, obj, vsync_period);
   return reinterpret_cast<intptr_t>(window);
 }
 
 }  // namespace ui