Add support for touch-action: manipulation

content/browser/renderer_host/input/touch_action_filter.cc

 // Copyright 2013 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 "content/browser/renderer_host/input/touch_action_filter.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
@@ skipping 43 matching lines @@
         if (allowed_touch_action_ == TOUCH_ACTION_PAN_Y)
           gesture_event->data.flingStart.velocityX = 0;
       }
       return FilterScrollEndingGesture();
 
     case WebInputEvent::GestureScrollEnd:
       return FilterScrollEndingGesture();
 
     case WebInputEvent::GesturePinchBegin:
       DCHECK(!drop_pinch_gesture_events_);
-      if (allowed_touch_action_ == TOUCH_ACTION_AUTO) {
+      if (allowed_touch_action_ == TOUCH_ACTION_AUTO ||
+          allowed_touch_action_ & TOUCH_ACTION_PINCH_ZOOM) {
         // Pinch events are always bracketed by scroll events, and the W3C
         // standard touch-action provides no way to disable scrolling without
-        // also disabling pinching.
+        // also disabling pinching (validated by the IPC ENUM traits).
+        DCHECK(allowed_touch_action_ == TOUCH_ACTION_AUTO ||
+            allowed_touch_action_ == TOUCH_ACTION_MANIPULATION);
         DCHECK(!drop_scroll_gesture_events_);
       } else {
         drop_pinch_gesture_events_ = true;
       }
       return drop_pinch_gesture_events_;
 
     case WebInputEvent::GesturePinchUpdate:
       return drop_pinch_gesture_events_;
 
     case WebInputEvent::GesturePinchEnd:
@@ skipping 105 matching lines @@
   if (ta2 == TOUCH_ACTION_AUTO)
     return ta1;
 
   // Only the true flags are left - take their intersection.
   if (!(ta1 & ta2))
     return TOUCH_ACTION_NONE;
   return static_cast<TouchAction>(ta1 & ta2);
 }
 
 }