Keep track of coalesced events in main thread event queue

third_party/WebKit/public/platform/WebCoalescedInputEvent.h

Index: third_party/WebKit/public/platform/WebCoalescedInputEvent.h
diff --git a/third_party/WebKit/public/platform/WebCoalescedInputEvent.h b/third_party/WebKit/public/platform/WebCoalescedInputEvent.h
index 94dd15021d2ff30317fc9fa3f7002c784ce1b970..e1a282a542c6f01cd7fa08d2fe06723689344ddb 100644
--- a/third_party/WebKit/public/platform/WebCoalescedInputEvent.h
+++ b/third_party/WebKit/public/platform/WebCoalescedInputEvent.h
@@ -24,8 +24,8 @@ using WebScopedInputEvent =
 // coalesced events. The event could be any events defined in WebInputEvent.h.
 class BLINK_COMMON_EXPORT WebCoalescedInputEvent {
  public:
-  WebCoalescedInputEvent(WebScopedInputEvent);
-  WebCoalescedInputEvent(const WebInputEvent&);
+  explicit WebCoalescedInputEvent(WebScopedInputEvent);
+  explicit WebCoalescedInputEvent(const WebInputEvent&);
   WebCoalescedInputEvent(const WebInputEvent&,
                          const std::vector<const WebInputEvent*>&);
 
@@ -33,7 +33,7 @@ class BLINK_COMMON_EXPORT WebCoalescedInputEvent {
   void addCoalescedEvent(const blink::WebInputEvent&);
   const WebInputEvent& event() const;
   size_t coalescedEventSize() const;
-  const WebInputEvent* coalescedEvent(int index) const;
+  const WebInputEvent& coalescedEvent(size_t index) const;
   std::vector<const WebInputEvent*> getCoalescedEventsPointers() const;
 
  private: