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 ef96e0d164aa88ee1cd176f2557c59da35aa1056..81e794383f494de5966a3f87e7b6b4a05983c1bb 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -226,6 +226,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   void DidStopFlinging() override;
 
 #if defined(OS_WIN)
+  void SetLegacyRenderWidgetHostHWND(LegacyRenderWidgetHostHWND* legacy_hwnd);
   virtual void SetParentNativeViewAccessible(
       gfx::NativeViewAccessible accessible_parent) override;
   virtual gfx::NativeViewId GetParentForWindowlessPlugin() const override;
@@ -325,9 +326,6 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
 
   // Updates the cursor clip region. Used for mouse locking.
   void UpdateMouseLockRegion();
-
-  // Notification that the LegacyRenderWidgetHostHWND was destroyed.
-  void OnLegacyWindowDestroyed();
 #endif
 
   void DisambiguationPopupRendered(bool success, const SkBitmap& result);
@@ -594,17 +592,7 @@ 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
 
   bool has_snapped_to_boundary_;