Use monotonic time to record the touch input latency in Blink.

Use monotonic time to record the touch input latency in Blink.

Since PlatformEvent uses monotonical time stamp, we should use monotonicallyIncreasingTime
instead of currentTime to record the touch event latency in Blink.

BUG=617984
Review-Url: https://codereview.chromium.org/2044923004
Cr-Commit-Position: refs/heads/master@{#398712}
(cherry picked from commit c5707d4d2131cf90f2fe8c9887a1c95c83a12812)

Committed: https://chromium.googlesource.com/chromium/src/+/da0f532810ea5326996237262c0e0711d7c0e737

[lanwei, 2016-06-09 22:13:58]

Description was changed from

==========
Use monotonic time to record the touch input latency in Blink.

Since PlatformEvent uses monotonical time stamp, we should use
monotonicallyIncreasingTime
instead of currentTime to record the touch event latency in Blink.

BUG=617984

Review-Url: https://codereview.chromium.org/2044923004
Cr-Commit-Position: refs/heads/master@{#398712}
(cherry picked from commit c5707d4d2131cf90f2fe8c9887a1c95c83a12812)
==========

to

==========
Use monotonic time to record the touch input latency in Blink.

Since PlatformEvent uses monotonical time stamp, we should use
monotonicallyIncreasingTime
instead of currentTime to record the touch event latency in Blink.

BUG=617984

Review-Url: https://codereview.chromium.org/2044923004
Cr-Commit-Position: refs/heads/master@{#398712}
(cherry picked from commit c5707d4d2131cf90f2fe8c9887a1c95c83a12812)

Committed:
https://chromium.googlesource.com/chromium/src/+/da0f532810ea5326996237262c0e...
==========

[lanwei, 2016-06-09 22:13:59]

Committed patchset #1 (id:1) manually as
da0f532810ea5326996237262c0e0711d7c0e737.