Make code path for bounds changes getting to renderer less brittle

content/browser/web_contents/aura/constrained_windows_observer.h

Index: content/browser/web_contents/aura/constrained_windows_observer.h
diff --git a/content/browser/web_contents/aura/constrained_windows_observer.h b/content/browser/web_contents/aura/constrained_windows_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..4997e4dbb25ef83a5300f548c28e06305145a687
--- /dev/null
+++ b/content/browser/web_contents/aura/constrained_windows_observer.h
@@ -0,0 +1,45 @@
+// 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_CONSTRAINED_WINDOWS_OBSERVER_H__
+#define CONTENT_BROWSER_WEB_CONTENTS_AURA_CONSTRAINED_WINDOWS_OBSERVER_H__
+
+#include "base/compiler_specific.h"
+#include "content/common/content_export.h"
+#include "ui/aura/window_observer.h"
+
+namespace content {
+
+class WebContentsViewAura;
+
+class CONTENT_EXPORT ConstrainedWindowsObserver
+    : public aura::WindowObserver {
+public:
+  ConstrainedWindowsObserver(WebContentsViewAura* view);
+  virtual ~ConstrainedWindowsObserver();
+
+  // Overridden from aura::WindowObserver:
+  virtual void OnWindowAdded(aura::Window* new_window) OVERRIDE;
+  virtual void OnWillRemoveWindow(aura::Window* window) OVERRIDE;
+  virtual void OnWindowVisibilityChanged(aura::Window* window,
+                                         bool visible) OVERRIDE;
+  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;
+
+private:
+  void UpdateConstrainedWindows(aura::Window* exclude);
+
+  WebContentsViewAura* view_;
+  aura::Window* constrained_parent_;
+
+  DISALLOW_COPY_AND_ASSIGN(ConstrainedWindowsObserver);
+};
+
+}  //namespace content
+#endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_CONSTRAINED_WINDOWS_OBSERVER_H__