Fixes bug where Env/RootWindow would cache the wrong button

ui/base/event.cc

 // 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.
 
 #include "ui/base/event.h"
 
 #if defined(USE_X11)
 #include <X11/Xlib.h>
 #endif
 
@@ skipping 107 matching lines @@
 void LocatedEvent::UpdateForRootTransform(const Transform& root_transform) {
   // Transform has to be done at root level.
   DCHECK_EQ(root_location_.x(), location_.x());
   DCHECK_EQ(root_location_.y(), location_.y());
   gfx::Point3f p(location_);
   root_transform.TransformPointReverse(p);
   root_location_ = location_ = p.AsPoint();
 }
 
 MouseEvent::MouseEvent(const base::NativeEvent& native_event)
-    : LocatedEvent(native_event) {
+    : LocatedEvent(native_event),
+      changed_button_flags_(
+          GetChangedMouseButtonFlagsFromNative(native_event)) {
   if (type() == ET_MOUSE_PRESSED)
     SetClickCount(GetRepeatCount(*this));
 }
 
 MouseEvent::MouseEvent(EventType type,
                        const gfx::Point& location,
                        const gfx::Point& root_location,
                        int flags)
-    : LocatedEvent(type, location, root_location, flags) {
+    : LocatedEvent(type, location, root_location, flags),
+      changed_button_flags_(0) {
 }
 
 // static
 bool MouseEvent::IsRepeatedClickEvent(
     const MouseEvent& event1,
     const MouseEvent& event2) {
   // These values match the Windows defaults.
   static const int kDoubleClickTimeMS = 500;
   static const int kDoubleClickWidth = 4;
   static const int kDoubleClickHeight = 4;
@@ skipping 247 matching lines @@
 int GestureEvent::GetLowestTouchId() const {
   if (touch_ids_bitfield_ == 0)
     return -1;
   int i = -1;
   // Find the index of the least significant 1 bit
   while (!(1 << ++i & touch_ids_bitfield_));
   return i;
 }
 
 }  // namespace ui