mus: Change PointerWatcher to observe all pointer events, with moves optional.

services/ui/ws/window_tree.h

Index: services/ui/ws/window_tree.h
diff --git a/services/ui/ws/window_tree.h b/services/ui/ws/window_tree.h
index ff71bda9353ed8db5d10e749f9c1e815f6484f06..dec352e1b09b6719421e61c8bd8e347417c25dc2 100644
--- a/services/ui/ws/window_tree.h
+++ b/services/ui/ws/window_tree.h
@@ -337,6 +337,9 @@ class WindowTree : public mojom::WindowTree,
 
   void DispatchInputEventImpl(ServerWindow* target, const ui::Event& event);
 
+  // Returns true if the client has a pointer watcher and this event matches.
+  bool EventMatchesPointerWatcher(const ui::Event& event);
+
   // Calls OnChangeCompleted() on the client.
   void NotifyChangeCompleted(uint32_t change_id,
                              mojom::WindowManagerErrorCode error_code);
@@ -369,8 +372,9 @@ class WindowTree : public mojom::WindowTree,
       override;
   void SetCapture(uint32_t change_id, Id window_id) override;
   void ReleaseCapture(uint32_t change_id, Id window_id) override;
-  void SetEventObserver(mojom::EventMatcherPtr matcher,
-                        uint32_t observer_id) override;
+  void StartPointerWatcher(bool want_moves,
+                           uint32_t pointer_watcher_id) override;
+  void StopPointerWatcher() override;
   void SetWindowBounds(uint32_t change_id,
                        Id window_id,
                        const gfx::Rect& bounds) override;
@@ -484,12 +488,15 @@ class WindowTree : public mojom::WindowTree,
   // reasonable timeframe.
   bool janky_ = false;
 
-  // Set when the client is using SetEventObserver() to observe events,
-  // otherwise null.
-  std::unique_ptr<EventMatcher> event_observer_matcher_;
+  // Whether the client is observing pointer events.
+  bool has_pointer_watcher_ = false;
+
+  // For performance reasons, only send move events if the client explicitly
+  // requests them.
+  bool pointer_watcher_want_moves_ = false;
 
-  // The ID supplied by the client for the current event observer.
-  uint32_t event_observer_id_ = 0;
+  // The ID supplied by the client for the current pointer watcher.
+  uint32_t pointer_watcher_id_ = 0;
 
   // WindowManager the current event came from.
   WindowManagerState* event_source_wms_ = nullptr;