Make touch-based synthetic gesture take touch slop into account.

content/browser/renderer_host/input/synthetic_gesture_target_base.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/synthetic_gesture_target_base.h"
 
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/browser/renderer_host/ui_events_helper.h"
 #include "content/common/input/input_event.h"
 #include "content/common/input_messages.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/events/event.h"
 #include "ui/events/latency_info.h"
 
 using blink::WebInputEvent;
 using blink::WebTouchEvent;
 using blink::WebMouseEvent;
 using blink::WebMouseWheelEvent;
 
 namespace content {
 namespace {
 
 // This value was determined experimentally. It was sufficient to not cause a
 // fling on Android.
 const int kPointerAssumedStoppedTimeMs = 50;
 
+// SyntheticGestureTargetBase passes input events straight on to the renderer
+// without going through a gesture recognition framework. There is thus no touch
+// slop.
+// On platforms where input events are processed by a gesture recognizer

[jdduke (slow), 2013/12/02 16:29:43]

Nit: remove the sentence with "On platforms", I think it's clear enough with the
virtual method, and this isn't very visible.

[Dominik Grewe, 2013/12/02 16:42:26]

Done.

+// GetTouchSlopInDips() should be overwritten.
+const int kTouchSlopInDips = 0;
+
 }  // namespace
 
 SyntheticGestureTargetBase::SyntheticGestureTargetBase(
     RenderWidgetHostImpl* host)
     : host_(host) {
   DCHECK(host);
 }
 
 SyntheticGestureTargetBase::~SyntheticGestureTargetBase() {
 }
@@ skipping 65 matching lines @@
     SyntheticGestureParams::GestureSourceType gesture_source_type) const {
   return gesture_source_type == SyntheticGestureParams::MOUSE_INPUT ||
       gesture_source_type == SyntheticGestureParams::TOUCH_INPUT;
 }
 
 base::TimeDelta SyntheticGestureTargetBase::PointerAssumedStoppedTime()
     const {
   return base::TimeDelta::FromMilliseconds(kPointerAssumedStoppedTimeMs);
 }
 
+int SyntheticGestureTargetBase::GetTouchSlopInDips() const {
+  return kTouchSlopInDips;
+}
+
 }  // namespace content