Account for failure of coordinate space transformations in browser

content/browser/renderer_host/delegated_frame_host.h

 // Copyright 2014 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_DELEGATED_FRAME_HOST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_DELEGATED_FRAME_HOST_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 143 matching lines @@
   bool HasFrameSubscriber() const { return !!frame_subscriber_; }
   cc::FrameSinkId GetFrameSinkId();
   // Returns a null SurfaceId if this DelegatedFrameHost has not yet created
   // a compositor Surface.
   cc::SurfaceId SurfaceIdAtPoint(cc::SurfaceHittestDelegate* delegate,
                                  const gfx::Point& point,
                                  gfx::Point* transformed_point);
 
   // Given the SurfaceID of a Surface that is contained within this class'
   // Surface, find the relative transform between the Surfaces and apply it
-  // to a point. If a Surface has not yet been created this returns the
-  // same point with no transform applied.
-  gfx::Point TransformPointToLocalCoordSpace(
-      const gfx::Point& point,
-      const cc::SurfaceId& original_surface);
+  // to a point. Returns false if a Surface has not yet been created or if
+  // |original_surface| is not embedded within our current Surface.
+  bool TransformPointToLocalCoordSpace(const gfx::Point& point,
+                                       const cc::SurfaceId& original_surface,
+                                       gfx::Point* transformed_point);
 
   // Given a RenderWidgetHostViewBase that renders to a Surface that is
   // contained within this class' Surface, find the relative transform between
-  // the Surfaces and apply it to a point. If a Surface has not yet been
-  // created this returns the same point with no transform applied.
-  gfx::Point TransformPointToCoordSpaceForView(
-      const gfx::Point& point,
-      RenderWidgetHostViewBase* target_view);
+  // the Surfaces and apply it to a point. Returns false if a Surface has not
+  // yet been created or if |target_view| is not a descendant RWHV from our
+  // client.
+  bool TransformPointToCoordSpaceForView(const gfx::Point& point,
+                                         RenderWidgetHostViewBase* target_view,
+                                         gfx::Point* transformed_point);
 
   // Exposed for tests.
   cc::SurfaceId SurfaceIdForTesting() const {
     return cc::SurfaceId(frame_sink_id_, local_frame_id_);
   }
 
   const cc::LocalFrameId& LocalFrameIdForTesting() const {
     return local_frame_id_;
   }
 
@@ skipping 150 matching lines @@
   // YUV readback pipeline.
   std::unique_ptr<display_compositor::ReadbackYUVInterface>
       yuv_readback_pipeline_;
 
   std::unique_ptr<DelegatedFrameEvictor> delegated_frame_evictor_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_DELEGATED_FRAME_HOST_H_