mus: Add watcher for all touch events.

services/ui/public/cpp/window_tree_client.h

Index: services/ui/public/cpp/window_tree_client.h
diff --git a/services/ui/public/cpp/window_tree_client.h b/services/ui/public/cpp/window_tree_client.h
index 07b6635c5f0a2d65b7d0b31ad193d341250120a3..50e29f3747ec69eaf2ca5a6ee4c5031b474d0167 100644
--- a/services/ui/public/cpp/window_tree_client.h
+++ b/services/ui/public/cpp/window_tree_client.h
@@ -179,7 +179,8 @@ class WindowTreeClient : public mojom::WindowTreeClient,
   // See description in window_tree.mojom. When an existing event observer is
   // updated or cleared then any future events from the server for that observer
   // will be ignored.
-  void SetEventObserver(mojom::EventMatcherPtr matcher);
+  uint32_t AddEventObserver(mojom::EventMatcherPtr matcher);
+  void RemoveEventObserver(uint32_t event_observer_id);
 
   // Performs a window move. |callback| will be asynchronously called with the
   // whether the move loop completed successfully.
@@ -307,9 +308,9 @@ class WindowTreeClient : public mojom::WindowTreeClient,
   void OnWindowInputEvent(uint32_t event_id,
                           Id window_id,
                           std::unique_ptr<ui::Event> event,
-                          uint32_t event_observer_id) override;
+                          mojo::Array<uint32_t> event_observer_ids) override;
   void OnEventObserved(std::unique_ptr<ui::Event> event,
-                       uint32_t event_observer_id) override;
+                       mojo::Array<uint32_t> event_observer_ids) override;
   void OnWindowFocused(Id focused_window_id) override;
   void OnWindowPredefinedCursorChanged(Id window_id,
                                        mojom::Cursor cursor) override;
@@ -359,6 +360,10 @@ class WindowTreeClient : public mojom::WindowTreeClient,
       const gfx::Vector2d& offset,
       const gfx::Insets& hit_area) override;
 
+  // Returns true if there is an id in event_observer_ids_ that matches
+  // this event_observer_id.
+  bool MatchEventObserverId(uint32_t event_observer_id);
+
   // The one int in |cursor_location_mapping_|. When we read from this
   // location, we must always read from it atomically.
   base::subtle::Atomic32* cursor_location_memory() {
@@ -410,10 +415,9 @@ class WindowTreeClient : public mojom::WindowTreeClient,
       window_manager_internal_;
   mojom::WindowManagerClientAssociatedPtr window_manager_internal_client_;
 
-  bool has_event_observer_ = false;
-
   // Monotonically increasing ID for event observers.
   uint32_t event_observer_id_ = 0u;
+  std::vector<uint32_t> event_observer_ids_;
 
   // The current change id for the client.
   uint32_t current_move_loop_change_ = 0u;