The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919

commit 5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919
Author: dominickn <dominickn@chromium.org>
Date: Fri Mar 25 03:06:22 2016

Replace MouseWheel events with GestureScrollBegin in WebContentsObserver::DidGetUserInteraction

 crbug.com/568183  implements GestureScrollBegin for mouse wheel events.
Once this has landed, the mouse event coalescing currently performed by
WebContentsObserver::DidGetUserInteraction will be redundant.

This CL removes the mouse event coalescing, and changes
DidGetUserInteraction to fire on GestureScrollBegin events. The event
type used to signal scrolls in the method is changed from MouseWheel to
GestureScrollBegin, as scroll events will now be fired on mobile scrolls
as well as wheel scrolls. Finally, in clients of DidGetUserInteraction,
MouseWheel is replaced with GestureScrollBegin, and references to
'wheel' are replaced with 'scroll'.

BUG= 590612 

Review URL: https://codereview.chromium.org/1748553002

Cr-Commit-Position: refs/heads/master@{#383231}

[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/chrome/browser/download/download_request_limiter.cc
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/chrome/browser/download/download_request_limiter_unittest.cc
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/chrome/browser/engagement/site_engagement_helper.cc
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/chrome/browser/engagement/site_engagement_helper_unittest.cc
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/chrome/browser/engagement/site_engagement_metrics.h
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/chrome/browser/engagement/site_engagement_service_unittest.cc
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/chrome/browser/external_protocol/external_protocol_observer.cc
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/content/browser/renderer_host/render_widget_host_delegate.h
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/content/browser/renderer_host/render_widget_host_impl.cc
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/content/browser/renderer_host/render_widget_host_impl.h
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/content/public/browser/web_contents_observer.h
[modify] https://crrev.com/5cc29a417bcb7b86ca8ebc4304eefa4d74a7e919/tools/metrics/histograms/histograms.xml