Refactor browser process coordinate transformation methods

cc/surfaces/surface_hittest.cc

 // Copyright 2015 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.
 
 #include "cc/surfaces/surface_hittest.h"
 
 #include "cc/output/compositor_frame.h"
 #include "cc/output/delegated_frame_data.h"
 #include "cc/quads/draw_quad.h"
 #include "cc/quads/render_pass_draw_quad.h"
@@ skipping 37 matching lines @@
   // Reset the output transform to identity.
   if (transform)
     *transform = gfx::Transform();
 
   std::set<const RenderPass*> referenced_passes;
   return GetTransformToTargetSurfaceInternal(root_surface_id, target_surface_id,
                                              RenderPassId(), &referenced_passes,
                                              transform);
 }
 
+bool SurfaceHittest::TransformPointToTargetSurface(
+    const SurfaceId& original_surface_id,
+    const SurfaceId& target_surface_id,
+    gfx::Point* point) {
+  gfx::Transform transform;
+  // Two possibilities need to be considered: original_surface_id can be
+  // embedded in target_surface_id, or vice versa.
+  if (GetTransformToTargetSurface(target_surface_id, original_surface_id,
+                                  &transform)) {
+    if (transform.GetInverse(&transform))
+      transform.TransformPoint(point);
+    else
+      return false;
+  } else if (GetTransformToTargetSurface(original_surface_id, target_surface_id,
+                                         &transform)) {
+    // No need to invert the transform matrix in this case.
+    transform.TransformPoint(point);
+  } else {
+    return false;
+  }
+
+  return true;
+}
+
 bool SurfaceHittest::GetTargetSurfaceAtPointInternal(
     const SurfaceId& surface_id,
     const RenderPassId& render_pass_id,
     const gfx::Point& point_in_root_target,
     std::set<const RenderPass*>* referenced_passes,
     SurfaceId* out_surface_id,
     gfx::Transform* out_transform) {
   const RenderPass* render_pass =
       GetRenderPassForSurfaceById(surface_id, render_pass_id);
   if (!render_pass)
@@ skipping 207 matching lines @@
     return false;
   }
 
   *point_in_quad_space = point_in_render_pass_space;
   target_to_quad_transform->TransformPoint(point_in_quad_space);
 
   return quad->rect.Contains(*point_in_quad_space);
 }
 
 }  // namespace cc