Make code path for bounds changes getting to renderer less brittle

content/browser/web_contents/aura/native_view_screen_bounds_observer.h

Index: content/browser/web_contents/aura/native_view_screen_bounds_observer.h
diff --git a/content/browser/web_contents/aura/native_view_screen_bounds_observer.h b/content/browser/web_contents/aura/native_view_screen_bounds_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..0c7bee1edad939db22a5bc5d14a4c95f756db0cd
--- /dev/null
+++ b/content/browser/web_contents/aura/native_view_screen_bounds_observer.h
@@ -0,0 +1,66 @@
+// Copyright (c) 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.
+
+#ifndef CONTENT_BROWSER_WEB_CONTENTS_AURA_NATIVE_VIEW_SCREEN_BOUNDS_OBSERVER_H__
+#define CONTENT_BROWSER_WEB_CONTENTS_AURA_NATIVE_VIEW_SCREEN_BOUNDS_OBSERVER_H__
+
+#include <set>
+
+#include "base/compiler_specific.h"
+#include "content/common/content_export.h"
+#include "ui/aura/root_window_observer.h"
+#include "ui/aura/window_observer.h"
+
+namespace content {
+
+class CONTENT_EXPORT NativeViewScreenBoundsObserverDelegate {
+ public:
+  NativeViewScreenBoundsObserverDelegate() { }
+  virtual ~NativeViewScreenBoundsObserverDelegate() { }
+
+  virtual void OnScreenPositionChanged() = 0;
+  virtual void OnScreenBoundsChanged() = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(NativeViewScreenBoundsObserverDelegate);
+};
+
+class CONTENT_EXPORT NativeViewScreenBoundsObserver
+    : public aura::WindowObserver,
+      public aura::RootWindowObserver {
+ public:
+  explicit NativeViewScreenBoundsObserver
+      (NativeViewScreenBoundsObserverDelegate* delegate,
+       aura::Window* window);
+  virtual ~NativeViewScreenBoundsObserver();
+
+  // Overridden from aura::WindowObserver:
+  virtual void OnWindowParentChanged(aura::Window* window,
+                                     aura::Window* parent) OVERRIDE;
+  virtual void OnWindowBoundsChanged(aura::Window* window,
+                                     const gfx::Rect& old_bounds,
+                                     const gfx::Rect& new_bounds) OVERRIDE;
+  virtual void OnWindowAddedToRootWindow(aura::Window* window) OVERRIDE;
+  virtual void OnWindowRemovingFromRootWindow(aura::Window* window) OVERRIDE;
+
+  // Overridden RootWindowObserver:
+  virtual void OnRootWindowHostMoved(const aura::RootWindow* root,
+                                     const gfx::Point& new_origin) OVERRIDE;
+
+ private:
+  friend class NativeViewScreenBoundsObserverTest;
+
+  std::set<aura::Window*> CollectAllWindowsToRoot(aura::Window* window);
+  void AddToObserved(const std::set<aura::Window*>& windows);
+  void RemoveFromObserved(const std::set<aura::Window*>& windows);
+
+  NativeViewScreenBoundsObserverDelegate* delegate_;
+  aura::Window* window_;
+  std::set<aura::Window*> observed_;
+
+  DISALLOW_COPY_AND_ASSIGN(NativeViewScreenBoundsObserver);
+};
+
+}  // namespace content
+#endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_NATIVE_VIEW_SCREEN_BOUNDS_OBSERVER_H__