Reduce jank from favicon downscaling.

Reduce jank from favicon downscaling.

This refactors the favicon decode+downscaling+reencode logic into a
utility method and calls it on the history thread instead of
janking the UI thread.  (I left in a call in the original site as a
fallback path, but it will typically early-return as the work was
already done.)

I also added TRACE_EVENTs to help diagnose future performance issues.

BUG=644573
Review-Url: https://codereview.chromium.org/2313563002
Cr-Commit-Position: refs/heads/master@{#417190}
(cherry picked from commit 825375667cf20a127144357b2bcb24201f794e7d)

Committed: https://chromium.googlesource.com/chromium/src/+/ada426ca9d3b55c1a578fc30674dd2ac3f7ef5f5

[aelias_OOO_until_Jul13, 2016-09-09 00:48:05]

Description was changed from

==========
Reduce jank from favicon downscaling.

This refactors the favicon decode+downscaling+reencode logic into a
utility method and calls it on the history thread instead of
janking the UI thread.  (I left in a call in the original site as a
fallback path, but it will typically early-return as the work was
already done.)

I also added TRACE_EVENTs to help diagnose future performance issues.

BUG=644573

Review-Url: https://codereview.chromium.org/2313563002
Cr-Commit-Position: refs/heads/master@{#417190}
(cherry picked from commit 825375667cf20a127144357b2bcb24201f794e7d)
==========

to

==========
Reduce jank from favicon downscaling.

This refactors the favicon decode+downscaling+reencode logic into a
utility method and calls it on the history thread instead of
janking the UI thread.  (I left in a call in the original site as a
fallback path, but it will typically early-return as the work was
already done.)

I also added TRACE_EVENTs to help diagnose future performance issues.

BUG=644573

Review-Url: https://codereview.chromium.org/2313563002
Cr-Commit-Position: refs/heads/master@{#417190}
(cherry picked from commit 825375667cf20a127144357b2bcb24201f794e7d)

Committed:
https://chromium.googlesource.com/chromium/src/+/ada426ca9d3b55c1a578fc30674d...
==========

[aelias_OOO_until_Jul13, 2016-09-09 00:48:07]

Committed patchset #1 (id:1) manually as
ada426ca9d3b55c1a578fc30674dd2ac3f7ef5f5.