Mozart: Add ViewInspector contracts for hit testing.

services/ui/view_manager/view_tree_state.h

Index: services/ui/view_manager/view_tree_state.h
diff --git a/services/ui/view_manager/view_tree_state.h b/services/ui/view_manager/view_tree_state.h
index b270721ca979070c06da228c07fe7c08c2f55380..acb5941e5526ace679a32be995bae5e5b8f9cd98 100644
--- a/services/ui/view_manager/view_tree_state.h
+++ b/services/ui/view_manager/view_tree_state.h
@@ -52,9 +52,7 @@ class ViewTreeState {
 
   // The view tree's renderer.
   mojo::gfx::composition::Renderer* renderer() const { return renderer_.get(); }
-  void set_renderer(mojo::gfx::composition::RendererPtr renderer) {
-    renderer_ = renderer.Pass();
-  }
+  void SetRenderer(mojo::gfx::composition::RendererPtr renderer);
 
   // Gets the root of the view tree, or null if there is no root.
   ViewStub* root() const { return root_.get(); }
@@ -75,10 +73,20 @@ class ViewTreeState {
   bool layout_request_issued() const { return layout_request_issued_; }
   void set_layout_request_issued(bool value) { layout_request_issued_ = value; }
 
+  // Starts tracking a hit tester request.
+  // The request will be satisfied by the current renderer if possible.
+  // The callback will be invoked when the renderer changes.
+  void RequestHitTester(
+      mojo::InterfaceRequest<mojo::gfx::composition::HitTester>
+          hit_tester_request,
+      const mojo::ui::ViewInspector::GetHitTesterCallback& callback);
+
   const std::string& label() const { return label_; }
   const std::string& FormattedLabel() const;
 
  private:
+  void ClearHitTesterCallbacks(bool renderer_changed);
+
   mojo::ui::ViewTreeTokenPtr view_tree_token_;
   mojo::ui::ViewTreeListenerPtr view_tree_listener_;
 
@@ -94,6 +102,9 @@ class ViewTreeState {
   bool layout_request_pending_ = false;
   bool layout_request_issued_ = false;
 
+  std::vector<mojo::ui::ViewInspector::GetHitTesterCallback>
+      pending_hit_tester_callbacks_;
+
   base::WeakPtrFactory<ViewTreeState> weak_factory_;  // must be last
 
   DISALLOW_COPY_AND_ASSIGN(ViewTreeState);