Refactor browser process coordinate transformation methods

content/browser/renderer_host/render_widget_host_view_base.h

Index: content/browser/renderer_host/render_widget_host_view_base.h
diff --git a/content/browser/renderer_host/render_widget_host_view_base.h b/content/browser/renderer_host/render_widget_host_view_base.h
index 0a1e01ebc6587bb1cb833e6101e5325d1b13fbf0..3021fcf82b714d5229eecfad28317d84a0ad4787 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -241,15 +241,23 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
 
   // 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 the embedding 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.
-  virtual void TransformPointToLocalCoordSpace(
+  // coordinate space of an embedding, or embedded, Surface. Typically this

[lfg, 2016/07/28 19:58:58]

Is this comment change correct here? I can see that your changes to
CrossProcessFrameConnector allows the API to be used in either direction, but
not here. My understanding is that the |original_surface| always need to be
contained in the RWHVB's surface, but not the other way around.

[kenrb, 2016/07/28 21:19:08]

Since RenderWidgetHostViewChildFrame uses CrossProcessFrameConnector's method,
it can be either embedding or embedded by original_surface.
RenderWidgetHostViewAura and Mac require it to be embedded, but they are always
the root surface so there is no need to account for the other direction.

[lfg, 2016/07/28 21:30:27]

Acknowledged.

+  // 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(
       const gfx::Point& point,
-      const cc::SurfaceId& original_surface,
-      gfx::Point* transformed_point);
+      const cc::SurfaceId& original_surface);
+
+  // 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(
+      const gfx::Point& point,
+      RenderWidgetHostViewBase* target_view);
 
   //----------------------------------------------------------------------------
   // The following methods are related to IME.