Consolidate WebInputEvent coalescing logic

content/browser/renderer_host/input/touch_event_queue.cc

Index: content/browser/renderer_host/input/touch_event_queue.cc
diff --git a/content/browser/renderer_host/input/touch_event_queue.cc b/content/browser/renderer_host/input/touch_event_queue.cc
index 7447c7f42f987bf356858ea6f4fd603de51e60d0..50d21e12cbe3e1db3c5b31feda80f51c8953f8e3 100644
--- a/content/browser/renderer_host/input/touch_event_queue.cc
+++ b/content/browser/renderer_host/input/touch_event_queue.cc
@@ -20,8 +20,7 @@ typedef std::vector<TouchEventWithLatencyInfo> WebTouchEventWithLatencyList;
 class CoalescedWebTouchEvent {
  public:
   explicit CoalescedWebTouchEvent(const TouchEventWithLatencyInfo& event)
-      : coalesced_event_(event),
-        ignore_ack_(false) {
+      : coalesced_event_(event) {
     events_.push_back(event);
     TRACE_EVENT_ASYNC_BEGIN0(
         "input", "TouchEventQueue::QueueEvent", this);
@@ -36,31 +35,11 @@ class CoalescedWebTouchEvent {
   // the event was coalesced.
   bool CoalesceEventIfPossible(
       const TouchEventWithLatencyInfo& event_with_latency) {
-    if (coalesced_event_.event.type == WebKit::WebInputEvent::TouchMove &&
-        event_with_latency.event.type == WebKit::WebInputEvent::TouchMove &&
-        coalesced_event_.event.modifiers ==
-        event_with_latency.event.modifiers &&
-        coalesced_event_.event.touchesLength ==
-        event_with_latency.event.touchesLength &&
-        !ignore_ack_) {
+    if (!ignore_ack_ &&
+        coalesced_event_.TryCoalesceWith(event_with_latency)) {
       TRACE_EVENT_INSTANT0(
           "input", "TouchEventQueue::MoveCoalesced", TRACE_EVENT_SCOPE_THREAD);
       events_.push_back(event_with_latency);
-      // The WebTouchPoints include absolute position information. So it is
-      // sufficient to simply replace the previous event with the new event.
-      // However, it is necessary to make sure that all the points have the
-      // correct state, i.e. the touch-points that moved in the last event, but
-      // didn't change in the current event, will have Stationary state. It is
-      // necessary to change them back to Moved state.
-      const WebKit::WebTouchEvent last_event = coalesced_event_.event;
-      const ui::LatencyInfo last_latency = coalesced_event_.latency;
-      coalesced_event_ = event_with_latency;
-      coalesced_event_.latency.MergeWith(last_latency);
-      for (unsigned i = 0; i < last_event.touchesLength; ++i) {
-        if (last_event.touches[i].state == WebKit::WebTouchPoint::StateMoved)
-          coalesced_event_.event.touches[i].state =
-              WebKit::WebTouchPoint::StateMoved;
-      }
       return true;
     }