Add support for touch-action: pinch-zoom.

ui/events/blink/blink_event_util.cc

 // Copyright 2015 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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/events/blink/blink_event_util.h"
 
 #include <stddef.h>
@@ skipping 279 matching lines @@
       gesture.data.longPress.height = details.bounding_box_f().height();
       break;
     case ET_GESTURE_TWO_FINGER_TAP:
       gesture.type = blink::WebInputEvent::GestureTwoFingerTap;
       gesture.data.twoFingerTap.firstFingerWidth = details.first_finger_width();
       gesture.data.twoFingerTap.firstFingerHeight =
           details.first_finger_height();
       break;
     case ET_GESTURE_SCROLL_BEGIN:
       gesture.type = WebInputEvent::GestureScrollBegin;
+      gesture.data.scrollBegin.pointerCount = details.touch_points();
       gesture.data.scrollBegin.deltaXHint = details.scroll_x_hint();
       gesture.data.scrollBegin.deltaYHint = details.scroll_y_hint();
       break;
     case ET_GESTURE_SCROLL_UPDATE:
       gesture.type = WebInputEvent::GestureScrollUpdate;
       gesture.data.scrollUpdate.deltaX = details.scroll_x();
       gesture.data.scrollUpdate.deltaY = details.scroll_y();
       gesture.data.scrollUpdate.previousUpdateInSequencePrevented =
           details.previous_scroll_update_in_sequence_prevented();
       break;
@@ skipping 208 matching lines @@
       return blink::WebInputEvent::IsRight;
     case DomKeyLocation::NUMPAD:
       return blink::WebInputEvent::IsKeyPad;
     case DomKeyLocation::STANDARD:
       break;
   }
   return static_cast<blink::WebInputEvent::Modifiers>(0);
 }
 
 }  // namespace ui