Revert of Refactoring button field and its type

third_party/WebKit/Source/platform/PlatformMouseEvent.h

Index: third_party/WebKit/Source/platform/PlatformMouseEvent.h
diff --git a/third_party/WebKit/Source/platform/PlatformMouseEvent.h b/third_party/WebKit/Source/platform/PlatformMouseEvent.h
index 28c9056bdc42b040991c434655d775be5ad6f30e..c67cfb409c0d1b3582865b36cfcbf0899b2cc04f 100644
--- a/third_party/WebKit/Source/platform/PlatformMouseEvent.h
+++ b/third_party/WebKit/Source/platform/PlatformMouseEvent.h
@@ -33,6 +33,10 @@
 
 namespace blink {
 
+// These button numbers match the ones used in the DOM API, 0 through 2, except for NoButton which is specified in PointerEvent
+// spec but not in MouseEvent spec.
+enum MouseButton { NoButton = -1, LeftButton, MiddleButton, RightButton };
+
 class PlatformMouseEvent : public PlatformEvent {
 public:
     enum SyntheticEventType {
@@ -47,30 +51,31 @@ public:
 
     PlatformMouseEvent()
         : PlatformEvent(PlatformEvent::MouseMoved)
+        , m_button(NoButton)
         , m_clickCount(0)
         , m_synthesized(RealOrIndistinguishable)
     {
     }
 
-    PlatformMouseEvent(const IntPoint& position, const IntPoint& globalPosition, WebPointerProperties::Button button, EventType type, int clickCount, Modifiers modifiers, double timestamp)
+    PlatformMouseEvent(const IntPoint& position, const IntPoint& globalPosition, MouseButton button, EventType type, int clickCount, Modifiers modifiers, double timestamp)
         : PlatformEvent(type, modifiers, timestamp)
         , m_position(position)
         , m_globalPosition(globalPosition)
+        , m_button(button)
         , m_clickCount(clickCount)
         , m_synthesized(RealOrIndistinguishable)
     {
-        m_pointerProperties.button = button;
     }
 
-    PlatformMouseEvent(const IntPoint& position, const IntPoint& globalPosition, WebPointerProperties::Button button, EventType type, int clickCount, Modifiers modifiers, SyntheticEventType synthesized, double timestamp, WebPointerProperties::PointerType pointerType = WebPointerProperties::PointerType::Unknown)
+    PlatformMouseEvent(const IntPoint& position, const IntPoint& globalPosition, MouseButton button, EventType type, int clickCount, Modifiers modifiers, SyntheticEventType synthesized, double timestamp, WebPointerProperties::PointerType pointerType = WebPointerProperties::PointerType::Unknown)
         : PlatformEvent(type, modifiers, timestamp)
         , m_position(position)
         , m_globalPosition(globalPosition)
+        , m_button(button)
         , m_clickCount(clickCount)
         , m_synthesized(synthesized)
     {
         m_pointerProperties.pointerType = pointerType;
-        m_pointerProperties.button = button;
     }
 
     const WebPointerProperties& pointerProperties() const { return m_pointerProperties; }
@@ -78,6 +83,7 @@ public:
     const IntPoint& globalPosition() const { return m_globalPosition; }
     const IntPoint& movementDelta() const { return m_movementDelta; }
 
+    MouseButton button() const { return m_button; }
     int clickCount() const { return m_clickCount; }
     bool fromTouch() const { return m_synthesized == FromTouch; }
     SyntheticEventType getSyntheticEventType() const { return m_synthesized; }
@@ -96,6 +102,7 @@ protected:
     IntPoint m_globalPosition;
 
     IntPoint m_movementDelta;
+    MouseButton m_button;
     int m_clickCount;
     SyntheticEventType m_synthesized;