Fixes bug where Env/RootWindow would cache the wrong button

ui/base/events.h

 // Copyright (c) 2012 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 UI_BASE_EVENTS_H_
 #define UI_BASE_EVENTS_H_
 
 #include "base/event_types.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "ui/gfx/native_widget_types.h"
@@ skipping 138 matching lines @@
 UI_EXPORT int EventButtonFromNative(const base::NativeEvent& native_event);
 #endif
 
 // Returns the KeyboardCode from a native event.
 UI_EXPORT KeyboardCode KeyboardCodeFromNative(
     const base::NativeEvent& native_event);
 
 // Returns true if the message is a mouse event.
 UI_EXPORT bool IsMouseEvent(const base::NativeEvent& native_event);
 
+// Returns the flags of the button that changed during a press/release.
+UI_EXPORT int GetChangedMouseButtonFlagsFromNative(
+    const base::NativeEvent& native_event);
+
 // Gets the mouse wheel offset from a native event.
 UI_EXPORT int GetMouseWheelOffset(const base::NativeEvent& native_event);
 
 // Gets the touch id from a native event.
 UI_EXPORT int GetTouchId(const base::NativeEvent& native_event);
 
 // Gets the radius along the X/Y axis from a native event. Default is 1.0.
 UI_EXPORT float GetTouchRadiusX(const base::NativeEvent& native_event);
 UI_EXPORT float GetTouchRadiusY(const base::NativeEvent& native_event);
 
@@ skipping 41 matching lines @@
 UI_EXPORT int GetModifiersFromACCEL(const ACCEL& accel);
 
 // Returns true if |message| identifies a mouse event that was generated as the
 // result of a touch event.
 UI_EXPORT bool IsMouseEventFromTouch(UINT message);
 #endif
 
 }  // namespace ui
 
 #endif  // UI_BASE_EVENTS_H_