Add code to collect crash data for https://crbug.com/592319.

content/browser/renderer_host/render_widget_host_input_event_router.h

Index: content/browser/renderer_host/render_widget_host_input_event_router.h
diff --git a/content/browser/renderer_host/render_widget_host_input_event_router.h b/content/browser/renderer_host/render_widget_host_input_event_router.h
index b4123539c5831f6b124b6ba3e4bd72beb34c6dce..e846ea87b700ac87564922ed8405f6640a45b424 100644
--- a/content/browser/renderer_host/render_widget_host_input_event_router.h
+++ b/content/browser/renderer_host/render_widget_host_input_event_router.h
@@ -121,6 +121,22 @@ class CONTENT_EXPORT RenderWidgetHostInputEventRouter
   std::unordered_map<cc::SurfaceId, HittestData, cc::SurfaceIdHash>
       hittest_data_;
 
+  // Debugging data for https://crbug.com/592319.
+  // Data types declared here to simplify later removal, and understanding of
+  // the code while it's in this intermediate state.
+  static const unsigned kNumLastEventTypes = 5;
+  struct GestureQueueDebugData {
+    unsigned long number_of_gesture_targets_enqueued;
+    unsigned long number_of_gesture_targets_dequeued;
+    int last_gesture_event_types[kNumLastEventTypes];
+    int last_touch_event_types[kNumLastEventTypes];
+    unsigned next_gesture_event_index;
+    unsigned next_touch_event_index;
+
+    GestureQueueDebugData();
+  };
+  GestureQueueDebugData debug_data_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostInputEventRouter);
   FRIEND_TEST_ALL_PREFIXES(SitePerProcessBrowserTest,
                            InputEventRouterGestureTargetQueueTest);