Retest that we don't get empty gesture targets.

content/browser/renderer_host/render_widget_host_input_event_router.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.
 
 #include "content/browser/renderer_host/render_widget_host_input_event_router.h"
 
+#include "base/debug/dump_without_crashing.h"
 #include "cc/quads/surface_draw_quad.h"
 #include "cc/surfaces/surface_id_allocator.h"
 #include "cc/surfaces/surface_manager.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/frame_messages.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 
 namespace {
 
 void TransformEventTouchPositions(blink::WebTouchEvent* event,
@@ skipping 152 matching lines @@
   // means the GestureFlingCancel that always comes between ET_GESTURE_BEGIN and
   // GestureTapDown is sent to the previous target, in case it is still in a
   // fling.
   if (event->type == blink::WebInputEvent::GestureTapDown) {
     if (gesture_target_queue_.empty()) {
       LOG(ERROR) << "Gesture sequence start detected with no target available.";
       // Ignore this gesture sequence as no target is available.
       // TODO(wjmaclean): this only happens on Windows, and should not happen.
       // https://crbug.com/595422
       gesture_target_ = nullptr;
+      base::debug::DumpWithoutCrashing();
       return;
     }
 
     const GestureTargetData& data = gesture_target_queue_.front();
     gesture_target_ = data.target;
     gesture_delta_ = data.delta;
     gesture_target_queue_.pop_front();
   }
 
   if (!gesture_target_)
@@ skipping 94 matching lines @@
   if (owner_map_.find(cc::SurfaceIdAllocator::NamespaceForId(
           params.surface_id)) == owner_map_.end()) {
     return;
   }
   HittestData data;
   data.ignored_for_hittest = params.ignored_for_hittest;
   hittest_data_[params.surface_id] = data;
 }
 
 }  // namespace content