[Android] More eager gesture recognition hardening

content/browser/android/content_view_core_impl.cc

 // Copyright 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 "content/browser/android/content_view_core_impl.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
@@ skipping 1012 matching lines @@
   handling_touch_event_ = true;
 
   pending_touch_event_ =
       WebTouchEventBuilder::Build(motion_event, GetDpiScale());
 
   pending_gesture_packet_ =
       GestureEventPacket::FromTouch(pending_touch_event_);
 }
 
 void ContentViewCoreImpl::OnTouchEventHandlingEnd(JNIEnv* env, jobject obj) {
-  DCHECK(handling_touch_event_);
+  if (!handling_touch_event_)
+    return;
+
+  GestureEventPacket gesture_packet;
+  std::swap(gesture_packet, pending_gesture_packet_);
+
   handling_touch_event_ = false;
 
   RenderWidgetHostViewAndroid* rwhv = GetRenderWidgetHostViewAndroid();
   if (!rwhv)
     return;
 
   // Note: Order is important here, as the touch may be ack'ed synchronously
   TouchDispositionGestureFilter::PacketResult result =
-      touch_disposition_gesture_filter_.OnGestureEventPacket(
-          pending_gesture_packet_);
+      touch_disposition_gesture_filter_.OnGestureEventPacket(gesture_packet);
   if (result != TouchDispositionGestureFilter::SUCCESS) {
     NOTREACHED() << "Invalid touch gesture sequence detected.";
     return;
   }
   rwhv->SendTouchEvent(pending_touch_event_);
 }
 
 float ContentViewCoreImpl::GetTouchPaddingDip() {
   return 48.0f / GetDpiScale();
 }
@@ skipping 807 matching lines @@
       reinterpret_cast<ui::ViewAndroid*>(view_android),
       reinterpret_cast<ui::WindowAndroid*>(window_android));
   return reinterpret_cast<intptr_t>(view);
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content