Ignore gesture sequences that have no target.

content/browser/renderer_host/render_widget_host_input_event_router.cc

Index: content/browser/renderer_host/render_widget_host_input_event_router.cc
diff --git a/content/browser/renderer_host/render_widget_host_input_event_router.cc b/content/browser/renderer_host/render_widget_host_input_event_router.cc
index 9add2783f3f5751851f37785437dc00b853b52bc..3fd57796c7a78d2c74400dfb2cad1c5bec69914b 100644
--- a/content/browser/renderer_host/render_widget_host_input_event_router.cc
+++ b/content/browser/renderer_host/render_widget_host_input_event_router.cc
@@ -4,7 +4,6 @@
 
 #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"
@@ -26,18 +25,6 @@ void TransformEventTouchPositions(blink::WebTouchEvent* event,
 
 namespace content {
 
-// Code to assist debugging https://crbug.com/592319.
-RenderWidgetHostInputEventRouter::GestureQueueDebugData::GestureQueueDebugData()
-    : number_of_gesture_targets_enqueued(0),
-      number_of_gesture_targets_dequeued(0),
-      next_gesture_event_index(0),
-      next_touch_event_index(0) {
-  for (unsigned i = 0; i < kNumLastEventTypes; ++i) {
-    last_gesture_event_types[i] = blink::WebInputEvent::Undefined;
-    last_touch_event_types[i] = blink::WebInputEvent::Undefined;
-  }
-}
-
 void RenderWidgetHostInputEventRouter::OnRenderWidgetHostViewBaseDestroyed(
     RenderWidgetHostViewBase* view) {
   view->RemoveObserver(this);
@@ -184,11 +171,11 @@ void RenderWidgetHostInputEventRouter::RouteGestureEvent(
   // fling.
   if (event->type == blink::WebInputEvent::GestureTapDown) {
     if (gesture_target_queue_.empty()) {
-      // Collect data to assist debugging https://crbug.com/592319.
-      // We'll assume for now if there's no target that we should just ignore
-      // the event.
       LOG(ERROR) << "Gesture sequence start detected with no target available.";
-      base::debug::DumpWithoutCrashing();
+      // 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;
       return;
     }
 
@@ -196,16 +183,8 @@ void RenderWidgetHostInputEventRouter::RouteGestureEvent(
     gesture_target_ = data.target;
     gesture_delta_ = data.delta;
     gesture_target_queue_.pop_front();
-    // Code to assist debugging https://crbug.com/592319.
-    debug_data_.number_of_gesture_targets_dequeued++;
   }
 
-  // Code to assist debugging https://crbug.com/592319.
-  debug_data_.last_gesture_event_types[debug_data_.next_gesture_event_index] =
-      event->type;
-  debug_data_.next_gesture_event_index =
-      (debug_data_.next_gesture_event_index + 1) % kNumLastEventTypes;
-
   if (!gesture_target_)
     return;
 
@@ -218,12 +197,6 @@ void RenderWidgetHostInputEventRouter::RouteTouchEvent(
     RenderWidgetHostViewBase* root_view,
     blink::WebTouchEvent* event,
     const ui::LatencyInfo& latency) {
-  // Code to assist debugging https://crbug.com/592319.
-  debug_data_.last_touch_event_types[debug_data_.next_touch_event_index] =
-      event->type;
-  debug_data_.next_touch_event_index =
-      (debug_data_.next_touch_event_index + 1) % kNumLastEventTypes;
-
   switch (event->type) {
     case blink::WebInputEvent::TouchStart: {
       if (!active_touches_) {
@@ -243,8 +216,6 @@ void RenderWidgetHostInputEventRouter::RouteTouchEvent(
         // for the duration of the sequence.
         touch_delta_ = transformed_point - original_point;
         gesture_target_queue_.emplace_back(touch_target_, touch_delta_);
-        // Code to assist debugging https://crbug.com/592319.
-        debug_data_.number_of_gesture_targets_enqueued++;
 
         if (!touch_target_)
           return;