Add blink::WebInputEvent::IsPinchGestureEventType().

ui/web_dialogs/web_dialog_web_contents_delegate.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/web_dialogs/web_dialog_web_contents_delegate.h"
 
 #include "base/logging.h"
 #include "content/public/browser/web_contents.h"
 #include "third_party/WebKit/public/platform/WebGestureEvent.h"
 
@@ skipping 42 matching lines @@
     const WebContents* source) const {
   // This needs to return true so that we are allowed to be resized by our
   // contents.
   return true;
 }
 
 bool WebDialogWebContentsDelegate::PreHandleGestureEvent(
     WebContents* source,
     const blink::WebGestureEvent& event) {
   // Disable pinch zooming.
-  return event.GetType() == blink::WebGestureEvent::kGesturePinchBegin ||
-         event.GetType() == blink::WebGestureEvent::kGesturePinchUpdate ||
-         event.GetType() == blink::WebGestureEvent::kGesturePinchEnd;
+  return blink::WebInputEvent::IsPinchGestureEventType(event.GetType());
 }
 
 }  // namespace ui