Make code path for bounds changes getting to renderer less brittle

content/browser/web_contents/web_contents_view_aura.h

Index: content/browser/web_contents/web_contents_view_aura.h
diff --git a/content/browser/web_contents/web_contents_view_aura.h b/content/browser/web_contents/web_contents_view_aura.h
index 7d377b05594345d30268104aeb0c7d543fd51bf9..7aa1c7e705d5e8d464231b5dbb0af38e9160c494 100644
--- a/content/browser/web_contents/web_contents_view_aura.h
+++ b/content/browser/web_contents/web_contents_view_aura.h
@@ -10,6 +10,8 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "content/browser/renderer_host/overscroll_controller_delegate.h"
+#include "content/browser/web_contents/aura/constrained_windows_observer.h"
+#include "content/browser/web_contents/aura/native_view_screen_bounds_observer.h"
 #include "content/common/content_export.h"
 #include "content/port/browser/render_view_host_delegate_view.h"
 #include "content/port/browser/web_contents_view_port.h"
@@ -39,7 +41,8 @@ class CONTENT_EXPORT WebContentsViewAura
       NON_EXPORTED_BASE(public OverscrollControllerDelegate),
       public ui::ImplicitAnimationObserver,
       public aura::WindowDelegate,
-      public aura::client::DragDropDelegate {
+      public aura::client::DragDropDelegate,
+      public NativeViewScreenBoundsObserverDelegate {
  public:
   WebContentsViewAura(WebContentsImpl* web_contents,
                       WebContentsViewDelegate* delegate);
@@ -49,8 +52,9 @@ class CONTENT_EXPORT WebContentsViewAura
   void SetTouchEditableForTest(TouchEditableImplAura* touch_editable);
 
  private:
-  class WindowObserver;
-
+#if defined(OS_WIN)
+  friend ConstrainedWindowsObserver;
+#endif
   virtual ~WebContentsViewAura();
 
   void SizeChangedCommon(const gfx::Size& size);
@@ -183,13 +187,26 @@ class CONTENT_EXPORT WebContentsViewAura
   virtual void OnDragExited() OVERRIDE;
   virtual int OnPerformDrop(const ui::DropTargetEvent& event) OVERRIDE;
 
+  // Overriden from NativeViewScreenBoundsObserverDelegate
+  virtual void OnScreenPositionChanged() OVERRIDE;
+  virtual void OnScreenBoundsChanged() OVERRIDE;
+
   scoped_ptr<aura::Window> window_;
 
   // The window that shows the screenshot of the history page during an
   // overscroll navigation gesture.
   scoped_ptr<aura::Window> overscroll_window_;
 
-  scoped_ptr<WindowObserver> window_observer_;
+  // Observes the window associated with the view and its ancestors to track if
+  // the visible bounds of the window have changed. If so it sends an update of
+  // the associated screen rect to the renderer.
+  scoped_ptr<NativeViewScreenBoundsObserver> bounds_observer_;
+
+#if defined(OS_WIN)
+  // Tracks the set of constrained windows for NPAPI plugins and sends bounds
+  // updates when appropriate.
+  scoped_ptr<ConstrainedWindowsObserver> constrained_observer_;
+#endif
 
   // The WebContentsImpl whose contents we display.
   WebContentsImpl* web_contents_;