Made the CompositorAnimationObserver class usable

chrome/browser/chromeos/ui/accessibility_focus_ring_controller.cc

 // Copyright 2014 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 "chrome/browser/chromeos/ui/accessibility_focus_ring_controller.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/shell.h"
 #include "base/logging.h"
 #include "chrome/browser/chromeos/ui/focus_ring_layer.h"
@@ skipping 25 matching lines @@
 
 }  // namespace
 
 // static
 AccessibilityFocusRingController*
     AccessibilityFocusRingController::GetInstance() {
   return Singleton<AccessibilityFocusRingController>::get();
 }
 
 AccessibilityFocusRingController::AccessibilityFocusRingController()
-    : compositor_(NULL) {
+    : compositor_(nullptr) {
 }
 
 AccessibilityFocusRingController::~AccessibilityFocusRingController() {
 }
 
 void AccessibilityFocusRingController::SetFocusRing(
     const std::vector<gfx::Rect>& rects) {
   rects_ = rects;
   Update();
 }
@@ skipping 16 matching lines @@
     gfx::Rect bounds = rings_[0].GetBounds();
     gfx::Display display =
       gfx::Screen::GetNativeScreen()->GetDisplayMatching(bounds);
     aura::Window* root_window = ash::Shell::GetInstance()->display_controller()
         ->GetRootWindowForDisplayId(display.id());
     ui::Compositor* compositor = root_window->layer()->GetCompositor();
     if (!compositor || root_window != layers_[0]->root_window()) {
       layers_[0]->Set(rings_[0]);
       if (compositor_ && compositor_->HasAnimationObserver(this)) {
         compositor_->RemoveAnimationObserver(this);
-        compositor_ = NULL;
+        compositor_ = nullptr;
       }
       continue;
     }
 
     focus_change_time_ = base::TimeTicks::Now();
     if (!compositor->HasAnimationObserver(this)) {
       compositor_ = compositor;
       compositor_->AddAnimationObserver(this);
     }
   }
@@ skipping 208 matching lines @@
   // focus change, so we just treat those as a delta of zero.
   if (timestamp < focus_change_time_)
     timestamp = focus_change_time_;
 
   base::TimeDelta delta = timestamp - focus_change_time_;
   base::TimeDelta transition_time =
       base::TimeDelta::FromMilliseconds(kTransitionTimeMilliseconds);
   if (delta >= transition_time) {
     layers_[0]->Set(rings_[0]);
     compositor_->RemoveAnimationObserver(this);
-    compositor_ = NULL;
+    compositor_ = nullptr;
     return;
   }
 
   double fraction = delta.InSecondsF() / transition_time.InSecondsF();
 
   // Ease-in effect.
   fraction = pow(fraction, 0.3);
 
   layers_[0]->Set(AccessibilityFocusRing::Interpolate(
       previous_rings_[0], rings_[0], fraction));
 }
 
+void AccessibilityFocusRingController::OnCompositingShuttingDown(
+    ui::Compositor* compositor) {

[xiyuan, 2015/06/01 18:06:35]

nit: DCHECK_EQ(compositor_, compositor);

+  if (compositor_) {
+    compositor_->RemoveAnimationObserver(this);
+  }
+  compositor_ = nullptr;
+}
+
 }  // namespace chromeos