All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=804328

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=bf26d34f1114a99812285df66f80d6293ccd4c2de26370bf74c7f3020ed82400


Bot(s) for this bug's original alert(s):

linux-release

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/11f893c4840000

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/11f893c4840000

blink/canvas: Switch Canvas to use cc's ImageDecodeCache.
By khushalsagar@chromium.org · Fri Jan 19 19:47:47 2018
chromium @ 60916ba1169d9207e048e2eca290c946ba37fcad

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

curious if my fix to at-raster handling here (https://chromium-review.googlesource.com/c/chromium/src/+/879064) will improve this. I imagine it will to some extent, so I'd start with it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ec5246d62d67feb1992c0fc61add8160f5b5309c

commit ec5246d62d67feb1992c0fc61add8160f5b5309c
Author: Eric Karl <ericrk@chromium.org>
Date: Mon Jan 22 22:50:26 2018

Adjust purging of unlocked discardable in GPU Image Decode Cache

We were incorrectly purging unlocked discardable to "make room" in the
cache, although unlocked entries don't take up room. This resulted in
non-optimal cache purging when we hit at-raster scenarios.

Now that all cached items are discardable, this change removes all
purging other than that needed to handle our max items in cache limit.

Bug:  802819 ,  804328 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I5cece605bbd40283073c075e78b36867c8c7efbf
Reviewed-on: https://chromium-review.googlesource.com/879064
Commit-Queue: Eric Karl <ericrk@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531032}
[modify] https://crrev.com/ec5246d62d67feb1992c0fc61add8160f5b5309c/cc/tiles/gpu_image_decode_cache.cc
[modify] https://crrev.com/ec5246d62d67feb1992c0fc61add8160f5b5309c/cc/tiles/gpu_image_decode_cache_unittest.cc

99% of the alerts filed were due to a decrease/increase pair that occurred in ref as well, probably a bot issue, and almost certainly not due to this change. Marked those alerts as invalid.

There is one remaining test which regressed. It didn't improve with the patch in #5, so  more investigation is needed.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7845c4435ff562dd058ec2af0d7269d73abce7a7

commit 7845c4435ff562dd058ec2af0d7269d73abce7a7
Author: Eric Karl <ericrk@chromium.org>
Date: Tue Jan 30 18:38:17 2018

Adjust purging of unlocked discardable in GPU Image Decode Cache

We were incorrectly purging unlocked discardable to "make room" in the
cache, although unlocked entries don't take up room. This resulted in
non-optimal cache purging when we hit at-raster scenarios.

Now that all cached items are discardable, this change removes all
purging other than that needed to handle our max items in cache limit.

TBR=ericrk@chromium.org

(cherry picked from commit ec5246d62d67feb1992c0fc61add8160f5b5309c)

Bug:  802819 ,  804328 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I5cece605bbd40283073c075e78b36867c8c7efbf
Reviewed-on: https://chromium-review.googlesource.com/879064
Commit-Queue: Eric Karl <ericrk@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#531032}
Reviewed-on: https://chromium-review.googlesource.com/893428
Reviewed-by: Eric Karl <ericrk@chromium.org>
Cr-Commit-Position: refs/branch-heads/3325@{#174}
Cr-Branched-From: bc084a8b5afa3744a74927344e304c02ae54189f-refs/heads/master@{#530369}
[modify] https://crrev.com/7845c4435ff562dd058ec2af0d7269d73abce7a7/cc/tiles/gpu_image_decode_cache.cc
[modify] https://crrev.com/7845c4435ff562dd058ec2af0d7269d73abce7a7/cc/tiles/gpu_image_decode_cache_unittest.cc