Fix reporting of TouchToFirstScroll latency metrics

Fix reporting of TouchToFirstScroll latency metrics

The metrics reported during GestureScrollUpdate contained mouse
wheel event gestures as well. This appeared as increased data
to be reported and showed a regression.

To fix this tag when a gesture scroll update is generated by a mouse
wheel event; and avoid these when reporting them to the uma metrics.

BUG=605147
Review URL: https://codereview.chromium.org/1911963005

Cr-Commit-Position: refs/heads/master@{#389271}
(cherry picked from commit 2148f54fea0ee0fa6d48d4cd87e204f6fbf7c9b9)

Committed: https://chromium.googlesource.com/chromium/src/+/b4e6e8438b71f84bc75c731b17e3651c3f357271

[dtapuska, 2016-04-26 14:58:03]

Description was changed from

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Fix reporting of TouchToFirstScroll latency metrics

The metrics reported during GestureScrollUpdate contained mouse
wheel event gestures as well. This appeared as increased data
to be reported and showed a regression.

To fix this tag when a gesture scroll update is generated by a mouse
wheel event; and avoid these when reporting them to the uma metrics.

BUG=605147

Review URL: https://codereview.chromium.org/1911963005

Cr-Commit-Position: refs/heads/master@{#389271}
(cherry picked from commit 2148f54fea0ee0fa6d48d4cd87e204f6fbf7c9b9)
==========

to

==========
Fix reporting of TouchToFirstScroll latency metrics

The metrics reported during GestureScrollUpdate contained mouse
wheel event gestures as well. This appeared as increased data
to be reported and showed a regression.

To fix this tag when a gesture scroll update is generated by a mouse
wheel event; and avoid these when reporting them to the uma metrics.

BUG=605147

Review URL: https://codereview.chromium.org/1911963005

Cr-Commit-Position: refs/heads/master@{#389271}
(cherry picked from commit 2148f54fea0ee0fa6d48d4cd87e204f6fbf7c9b9)

Committed:
https://chromium.googlesource.com/chromium/src/+/b4e6e8438b71f84bc75c731b17e3...
==========

[dtapuska, 2016-04-26 14:58:05]

Committed patchset #1 (id:1) manually as
b4e6e8438b71f84bc75c731b17e3651c3f357271.