Do not set the mouse event handler if Widget::SetCapture() fails

ui/views/widget/widget.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/views/widget/widget.h"
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 920 matching lines @@
 
 const NativeWidget* Widget::native_widget() const {
   return native_widget_;
 }
 
 NativeWidget* Widget::native_widget() {
   return native_widget_;
 }
 
 void Widget::SetCapture(View* view) {
+  if (!native_widget_->HasCapture()) {
+    native_widget_->SetCapture();
+
+    // Early return if setting capture was unsuccessful.
+    if (!native_widget_->HasCapture())
+      return;
+  }
+
   if (internal::NativeWidgetPrivate::IsMouseButtonDown())
     is_mouse_button_pressed_ = true;
   root_view_->SetMouseHandler(view);
-  if (!native_widget_->HasCapture())
-    native_widget_->SetCapture();
 }
 
 void Widget::ReleaseCapture() {
   if (native_widget_->HasCapture())
     native_widget_->ReleaseCapture();
 }
 
 bool Widget::HasCapture() {
   return native_widget_->HasCapture();
 }
@@ skipping 537 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // internal::NativeWidgetPrivate, NativeWidget implementation:
 
 internal::NativeWidgetPrivate* NativeWidgetPrivate::AsNativeWidgetPrivate() {
   return this;
 }
 
 }  // namespace internal
 }  // namespace views