mus: Allow embedder to intercept events.

components/mus/ws/window_tree.h

Index: components/mus/ws/window_tree.h
diff --git a/components/mus/ws/window_tree.h b/components/mus/ws/window_tree.h
index 2085ca77f897e4a2dae2810bb06e042f873b83f2..7f982142842e3f0c9556d80d641449b2b8a318d6 100644
--- a/components/mus/ws/window_tree.h
+++ b/components/mus/ws/window_tree.h
@@ -78,6 +78,11 @@ class WindowTree : public mojom::WindowTree,
 
   ClientSpecificId id() const { return id_; }
 
+  void set_embedder_intercepts_events() { embedder_intercepts_events_ = true; }
+  bool embedder_intercepts_events() const {
+    return embedder_intercepts_events_;
+  }
+
   const UserId& user_id() const { return user_id_; }
 
   mojom::WindowTreeClient* client() { return binding_->client(); }
@@ -148,7 +153,8 @@ class WindowTree : public mojom::WindowTree,
   bool SetWindowOpacity(const ClientWindowId& window_id, float opacity);
   bool SetFocus(const ClientWindowId& window_id);
   bool Embed(const ClientWindowId& window_id,
-             mojom::WindowTreeClientPtr client);
+             mojom::WindowTreeClientPtr client,
+             uint32_t flags);
   void DispatchInputEvent(ServerWindow* target, const ui::Event& event);
 
   bool IsWaitingForNewTopLevelWindow(uint32_t wm_change_id);
@@ -367,6 +373,7 @@ class WindowTree : public mojom::WindowTree,
                      mojom::SurfaceClientPtr client) override;
   void Embed(Id transport_window_id,
              mojom::WindowTreeClientPtr client,
+             uint32_t flags,
              const EmbedCallback& callback) override;
   void SetFocus(uint32_t change_id, Id transport_window_id) override;
   void SetCanFocus(Id transport_window_id, bool can_focus) override;
@@ -470,6 +477,7 @@ class WindowTree : public mojom::WindowTree,
 
   std::unique_ptr<WaitingForTopLevelWindowInfo>
       waiting_for_top_level_window_info_;
+  bool embedder_intercepts_events_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTree);
 };