UMA metrics for use count of wheel and touch scrolls.

cc/input/input_handler.h

 // Copyright 2011 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.
 
 #ifndef CC_INPUT_INPUT_HANDLER_H_
 #define CC_INPUT_INPUT_HANDLER_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 92 matching lines @@
     WHEEL,
     NON_BUBBLING_GESTURE
   };
 
   enum class TouchStartEventListenerType {
     NO_HANDLER,
     HANDLER,
     HANDLER_ON_SCROLLING_LAYER
   };
 
+  enum ScrollSourceInfo {
+    NONE,
+    SCROLLED_BY_TOUCH,

[bokan, 2017/03/09 17:31:03]

Make this a bitfield. i.e. SCROLLED_BY_TOUCH = 0x1, SCROLLED_BY_WHEEL = 0x2.
That way you can avoid the awkward translation in
LayerTreeHostImpl::UpdateScrollSourceInfo and just OR the values together.

[sahel, 2017/03/10 16:21:33]

Done.

+    SCROLLED_BY_WHEEL,
+    SCROLLED_BY_TOUCH_AND_WHEEL,
+  };
+
   // Binds a client to this handler to receive notifications. Only one client
   // can be bound to an InputHandler. The client must live at least until the
   // handler calls WillShutdown() on the client.
   virtual void BindToClient(InputHandlerClient* client) = 0;
 
   // Selects a layer to be scrolled using the |scroll_state| start position.
   // Returns SCROLL_STARTED if the layer at the coordinates can be scrolled,
   // SCROLL_ON_MAIN_THREAD if the scroll event should instead be delegated to
   // the main thread, or SCROLL_IGNORED if there is nothing to be scrolled at
   // the given coordinates.
@@ skipping 97 matching lines @@
   InputHandler() {}
   virtual ~InputHandler() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_INPUT_HANDLER_H_