Create only a single LegacyRenderWidgetHostHWND per WebContentsViewAura.

content/browser/renderer_host/render_widget_host_view_aura.h

Index: content/browser/renderer_host/render_widget_host_view_aura.h
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index e8c19d77a5c9f4c7343cac343c0359a4b008bb5c..edcb40a866e99d8f5f06051b5973420465b5b2d1 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -128,7 +128,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
     touch_editing_client_ = client;
   }
 
-  explicit RenderWidgetHostViewAura(RenderWidgetHost* host);
+  RenderWidgetHostViewAura(RenderWidgetHost* host);
 
   // RenderWidgetHostView implementation.
   virtual void InitAsChild(gfx::NativeView parent_view) OVERRIDE;
@@ -227,6 +227,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
       scoped_ptr<cc::CompositorFrame> frame) OVERRIDE;
 
 #if defined(OS_WIN)
+  void SetLegacyRenderWidgetHostHWND(LegacyRenderWidgetHostHWND* legacy_hwnd);
   virtual void SetParentNativeViewAccessible(
       gfx::NativeViewAccessible accessible_parent) OVERRIDE;
   virtual gfx::NativeViewId GetParentForWindowlessPlugin() const OVERRIDE;
@@ -324,9 +325,6 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
 
   // Updates the cursor clip region. Used for mouse locking.
   void UpdateMouseLockRegion();
-
-  // Notification that the LegacyRenderWidgetHostHWND was destroyed.
-  void OnLegacyWindowDestroyed();
 #endif
 
   // Method to indicate if this instance is shutting down or closing.
@@ -570,16 +568,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   // for accessibility, as the container for windowless plugins like
   // Flash/Silverlight, etc and for legacy drivers for trackpoints/trackpads,
   // etc.
-  // The LegacyRenderWidgetHostHWND instance is created during the first call
-  // to RenderWidgetHostViewAura::InternalSetBounds. The instance is destroyed
-  // when the LegacyRenderWidgetHostHWND hwnd is destroyed.
   content::LegacyRenderWidgetHostHWND* legacy_render_widget_host_HWND_;
-
-  // Set to true if the legacy_render_widget_host_HWND_ instance was destroyed
-  // by Windows. This could happen if the browser window was destroyed by
-  // DestroyWindow for e.g. This flag helps ensure that we don't try to create
-  // the LegacyRenderWidgetHostHWND instance again as that would be a futile
-  // exercise.
   bool legacy_window_destroyed_;
 #endif