Ensure RemoteViewportIntersection rect persists across frame navigations

content/browser/frame_host/cross_process_frame_connector.h

Index: content/browser/frame_host/cross_process_frame_connector.h
diff --git a/content/browser/frame_host/cross_process_frame_connector.h b/content/browser/frame_host/cross_process_frame_connector.h
index 641a51005299d443a1b1fa5a3043b0bef9048cca..25464303e6eccb18c1e9f7c74f2458d05afb4e75 100644
--- a/content/browser/frame_host/cross_process_frame_connector.h
+++ b/content/browser/frame_host/cross_process_frame_connector.h
@@ -133,12 +133,18 @@ class CONTENT_EXPORT CrossProcessFrameConnector {
   // Returns the view for the top-level frame under the same WebContents.
   RenderWidgetHostViewBase* GetRootRenderWidgetHostView();
 
+  gfx::Rect viewport_intersection() const {

[dcheng, 2017/05/30 19:54:11]

Nit: consider returning a const ref to avoid a copy

[kenrb, 2017/05/30 21:19:20]

Done.

+    return viewport_intersection_rect_;
+  }
+
   // Exposed for tests.
   RenderWidgetHostViewBase* GetRootRenderWidgetHostViewForTesting() {
     return GetRootRenderWidgetHostView();
   }
 
  private:
+  friend class MockCrossProcessFrameConnector;
+
   // Handlers for messages received from the parent frame.
   void OnFrameRectChanged(const gfx::Rect& frame_rect);
   void OnUpdateViewportIntersection(const gfx::Rect& viewport_intersection);
@@ -157,6 +163,7 @@ class CONTENT_EXPORT CrossProcessFrameConnector {
   RenderWidgetHostViewChildFrame* view_;
 
   gfx::Rect child_frame_rect_;
+  gfx::Rect viewport_intersection_rect_;
 
   bool is_scroll_bubbling_;
 };