Ensure RemoteViewportIntersection rect persists across frame navigations

content/browser/renderer_host/render_widget_host_view_base.h

 // Copyright (c) 2012 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_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 299 matching lines @@
   // entirely, which comes first.
   virtual bool IsRenderWidgetHostViewGuest();
 
   // Subclass identifier for RenderWidgetHostViewChildFrames. This is useful
   // to be able to know if this RWHV is embedded within another RWHV. If
   // other kinds of embeddable RWHVs are created, this should be renamed to
   // a more generic term -- in which case, static casts to RWHVChildFrame will
   // need to also be resolved.
   virtual bool IsRenderWidgetHostViewChildFrame();
 
+  // Notify the View that a screen rect update is being sent to the
+  // RenderWidget. Related platform-specific updates can be sent from here.
+  virtual void OnSendScreenRects() {}

[ncarter (slow), 2017/05/30 17:51:09]

Optional: "WillSendScreenRects" would be my pick to name this method. To me at
least, "OnX" connotes having gotten a legacy IPC message named X, though there
are certainly already a bunch of methods in this class (OnSurfaceChanged) that
don't follow that pattern -- so I am ok sticking with the On name if we want to
be consistent with those.

[kenrb, 2017/05/30 18:25:10]

That makes sense. Done.

+
   // Returns true if the current view is in virtual reality mode.
   virtual bool IsInVR() const;
 
   //----------------------------------------------------------------------------
   // The following methods are related to IME.
   // TODO(ekaramad): Most of the IME methods should not stay virtual after IME
   // is implemented for OOPIF. After fixing IME, mark the corresponding methods
   // non-virtual (https://crbug.com/578168).
 
   // Updates the state of the input method attached to the view.
@@ skipping 152 matching lines @@
   base::ObserverList<RenderWidgetHostViewBaseObserver> observers_;
 
   base::WeakPtrFactory<RenderWidgetHostViewBase> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewBase);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_