Added missing MainThreadScrollingReason in histograms.xml

ui/events/blink/input_handler_proxy.cc

 // Copyright 2013 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 "ui/events/blink/input_handler_proxy.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 359 matching lines @@
         // otherwise disrupt an in-progress touch scroll.
         if (fling_curve_)
           CancelCurrentFling();
       }
       break;
   }
 
   return DID_NOT_HANDLE;
 }
 
-void RecordMainThreadScrollingReasons(WebInputEvent::Type type,
-                                      uint32_t reasons) {
+void InputHandlerProxy::RecordMainThreadScrollingReasons(
+    WebInputEvent::Type type,
+    uint32_t reasons) {
   static const char* kGestureHistogramName =
       "Renderer4.MainThreadGestureScrollReason";
   static const char* kWheelHistogramName =
       "Renderer4.MainThreadWheelScrollReason";
 
   DCHECK(type == WebInputEvent::GestureScrollBegin ||
          type == WebInputEvent::MouseWheel);
 
   if (type != WebInputEvent::GestureScrollBegin &&
       type != WebInputEvent::MouseWheel) {
@@ skipping 912 matching lines @@
   // trigger a scroll, e.g., with a trivial time delta between fling updates.
   // Return true in this case to prevent early fling termination.
   if (std::abs(clipped_increment.width) < kScrollEpsilon &&
       std::abs(clipped_increment.height) < kScrollEpsilon)
     return true;
 
   return did_scroll;
 }
 
 }  // namespace ui