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.
         DCHECK(!drop_scroll_gesture_events_);
       } else {
         drop_pinch_gesture_events_ = true;
       }
       return drop_pinch_gesture_events_;
 
     case WebInputEvent::GesturePinchUpdate:
@@ skipping 90 matching lines @@
   // If there's no hint or it's perfectly diagonal, then allow the scroll.
   if (fabs(gesture_event.data.scrollBegin.deltaXHint) ==
       fabs(gesture_event.data.scrollBegin.deltaYHint))
     return false;
 
   // Determine the primary initial axis of the scroll, and check whether
   // panning along that axis is permitted.
   if (fabs(gesture_event.data.scrollBegin.deltaXHint) >
       fabs(gesture_event.data.scrollBegin.deltaYHint))
     return !(allowed_touch_action_ & TOUCH_ACTION_PAN_X);
   return !(allowed_touch_action_ & TOUCH_ACTION_PAN_Y);

[jdduke (slow), 2014/03/12 17:08:24]

Hmm, I think you need to allow the GestureScroll{Begin,End} through for
PINCH_ZOOM to work.

 }
 
 TouchAction TouchActionFilter::Intersect(TouchAction ta1, TouchAction ta2) {
   if (ta1 == TOUCH_ACTION_NONE || ta2 == TOUCH_ACTION_NONE)
     return TOUCH_ACTION_NONE;
   if (ta1 == TOUCH_ACTION_AUTO)
     return ta2;
   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);
 }
 
 }