Adopt "QuickScale" double-tap drag zoom code in the GestureProvider

content/browser/renderer_host/input/gesture_event_queue.cc

 // Copyright 2014 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/input/gesture_event_queue.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/strings/string_number_conversions.h"
 #include "content/browser/renderer_host/input/input_router.h"
@@ skipping 267 matching lines @@
 }
 
 void GestureEventQueue::MergeOrInsertScrollAndPinchEvent(
     const GestureEventWithLatencyInfo& gesture_event) {
   if (coalesced_gesture_events_.size() <= 1) {
     EnqueueEvent(gesture_event);
     return;
   }
   GestureEventWithLatencyInfo* last_event = &coalesced_gesture_events_.back();
   if (last_event->CanCoalesceWith(gesture_event)) {
-      last_event->CoalesceWith(gesture_event);
+    last_event->CoalesceWith(gesture_event);
     if (!combined_scroll_pinch_.IsIdentity()) {
       combined_scroll_pinch_.ConcatTransform(
           GetTransformForEvent(gesture_event));
     }
     return;
   }
   if (coalesced_gesture_events_.size() == 2 ||
       (coalesced_gesture_events_.size() == 3 && ignore_next_ack_) ||
       !ShouldTryMerging(gesture_event, *last_event)) {
     EnqueueEvent(gesture_event);
@@ skipping 80 matching lines @@
 
 void GestureEventQueue::EnqueueEvent(
     const GestureEventWithLatencyInfo& gesture_event) {
   coalesced_gesture_events_.push_back(gesture_event);
   // Scroll and pinch events contributing to |combined_scroll_pinch_| will be
   // manually added to the queue in |MergeOrInsertScrollAndPinchEvent()|.
   combined_scroll_pinch_ = gfx::Transform();
 }
 
 }  // namespace content