Extend MotionEvent to have tool type and button state

ui/events/gesture_detection/motion_event.h

Index: ui/events/gesture_detection/motion_event.h
diff --git a/ui/events/gesture_detection/motion_event.h b/ui/events/gesture_detection/motion_event.h
index 899aeea1c2ae7b8530cfbb1af15e57824bb2b29d..a1ed7ebad6ab47d71e9e567eb3005bcacd75df7f 100644
--- a/ui/events/gesture_detection/motion_event.h
+++ b/ui/events/gesture_detection/motion_event.h
@@ -16,7 +16,7 @@ namespace ui {
 class GESTURE_DETECTION_EXPORT MotionEvent {
  public:
   enum Action {
-    ACTION_DOWN,
+    ACTION_DOWN = 100,

[jdduke (slow), 2014/06/20 15:33:25]

Any reason for the 100/200?

[Changwan Ryu, 2014/06/20 21:00:34]

No specific reason. I just wanted to assign SOME distinct values so that when we
debug we can tell which enum value was used from debug message and log (such as
in ToAndroid... functions).

[jdduke (slow), 2014/06/20 21:19:41]

I see, let's stick with not assigning them specific non-zero values for now, as
the user would have to look at the header anyway to figure out the corresponding
value, and by then they'd know the context (whether it's action or tool type).

[Changwan Ryu, 2014/06/20 21:32:01]

Done.

     ACTION_UP,
     ACTION_MOVE,
     ACTION_CANCEL,
@@ -24,6 +24,20 @@ class GESTURE_DETECTION_EXPORT MotionEvent {
     ACTION_POINTER_UP,
   };
 
+  enum ToolType {
+    TOOL_TYPE_UNKNOWN = 200,
+    TOOL_TYPE_FINGER,
+    TOOL_TYPE_STYLUS,
+    TOOL_TYPE_MOUSE,
+  };
+
+  const static int BUTTON_NONE = 0;

[jdduke (slow), 2014/06/20 15:33:25]

I would go ahead and use an enum bit mask here, e.g., 

enum ButtonType {
  BUTTON_PRIMARY = 1 << 0,
  BUTTON_SECONDARY = 1 << 1,
  ...
}

[Changwan Ryu, 2014/06/20 21:00:34]

Done.

+  const static int BUTTON_PRIMARY = 1;
+  const static int BUTTON_SECONDARY = 2;
+  const static int BUTTON_TERTIARY = 4;
+  const static int BUTTON_BACK = 8;
+  const static int BUTTON_FORWARD = 16;
+
   // The implementer promises that |GetPointerId()| will never exceed this.
   enum { MAX_POINTER_ID = 31 };
 
@@ -53,6 +67,8 @@ class GESTURE_DETECTION_EXPORT MotionEvent {
                                size_t historical_index) const = 0;
   virtual float GetHistoricalY(size_t pointer_index,
                                size_t historical_index) const = 0;
+  virtual ToolType GetToolType(size_t pointer_index) const = 0;
+  virtual int GetButtonState() const = 0;
 
   virtual scoped_ptr<MotionEvent> Clone() const = 0;
   virtual scoped_ptr<MotionEvent> Cancel() const = 0;