Refactor browser process coordinate transformation methods

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 0af9c831f53c24cf17367b9515a7032308db4e97..5111607f3b1e844d7cd56b44145841e6f5775e0c 100644
--- a/content/browser/frame_host/cross_process_frame_connector.h
+++ b/content/browser/frame_host/cross_process_frame_connector.h
@@ -97,7 +97,20 @@ class CONTENT_EXPORT CrossProcessFrameConnector {
   void GetScreenInfo(blink::WebScreenInfo* results);
   void UpdateCursor(const WebCursor& cursor);
   gfx::Point TransformPointToRootCoordSpace(const gfx::Point& point,
-                                            cc::SurfaceId surface_id);
+                                            const cc::SurfaceId& surface_id);
+  // TransformPointToLocalCoordSpace() can only transform points between
+  // surfaces where one is embedded (not necessarily directly) within the
+  // other. For points that can be in sibling surfaces, they must first be
+  // converted to the root surface's coordinate space.
+  gfx::Point TransformPointToLocalCoordSpace(

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

Since this can be used to get transform matrixes between two arbitrary surfaces
(as long as they are embedded in each other), can you move it to SurfaceManager?
I think it makes more sense there. You'll still need to keep the DIPS/Pixels
conversion here, since SurfaceManager operates only in pixels.

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

SurfaceManager doesn't seem quite right because this isn't related to management
of Surfaces in any way. It seems more aligned with the hit testing code, since
this ends up basically being a wrapper for GetTransformToTargetSurface() that
let's us remove a small amount of code duplication between here and
DelegatedFrameHost. Accordingly I have added a method to the SurfaceHittest
class for this purpose.

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

Acknowledged.

+      const gfx::Point& point,
+      const cc::SurfaceId& original_surface,
+      const cc::SurfaceId& local_surface_id);
+  gfx::Point TransformPointToCoordSpaceForView(
+      const gfx::Point& point,
+      RenderWidgetHostViewBase* target_view,
+      const cc::SurfaceId& local_surface_id);
+
   // Pass acked touch events to the root view for gesture processing.
   void ForwardProcessAckedTouchEvent(const TouchEventWithLatencyInfo& touch,
                                      InputEventAckState ack_result);