Account for failure of coordinate space transformations in browser

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 239 matching lines @@
   virtual void ProcessGestureEvent(const blink::WebGestureEvent& event,
                                    const ui::LatencyInfo& latency) {}
 
   // Transform a point that is in the coordinate space of a Surface that is
   // embedded within the RenderWidgetHostViewBase's Surface to the
   // coordinate space of an embedding, or embedded, Surface. Typically this
   // means that a point was received from an out-of-process iframe's
   // RenderWidget and needs to be translated to viewport coordinates for the
   // root RWHV, in which case this method is called on the root RWHV with the
   // out-of-process iframe's SurfaceId.
-  // This does not transform points between surfaces where one does not
-  // contain the other. To transform between sibling surfaces, the point must
-  // be transformed to the root's coordinate space as an intermediate step.
-  virtual gfx::Point TransformPointToLocalCoordSpace(
+  // Returns false when this attempts to transform a point between coordinate
+  // spaces of surfaces where one does not contain the other. To transform
+  // between sibling surfaces, the point must be transformed to the root's
+  // coordinate space as an intermediate step.
+  virtual bool TransformPointToLocalCoordSpace(
       const gfx::Point& point,
-      const cc::SurfaceId& original_surface);
+      const cc::SurfaceId& original_surface,
+      gfx::Point* transformed_point);
 
   // Transform a point that is in the coordinate space for the current
   // RenderWidgetHostView to the coordinate space of the target_view.
-  virtual gfx::Point TransformPointToCoordSpaceForView(
+  virtual bool TransformPointToCoordSpaceForView(
       const gfx::Point& point,
-      RenderWidgetHostViewBase* target_view);
+      RenderWidgetHostViewBase* target_view,
+      gfx::Point* transformed_point);
 
   // TODO(kenrb, wjmaclean): This is a temporary subclass identifier for
   // RenderWidgetHostViewGuests that is needed for special treatment during
   // input event routing. It can be removed either when RWHVGuests properly
   // support direct mouse event routing, or when RWHVGuest is removed
   // 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
@@ skipping 214 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_