All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=897140

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=32c8b4069286a68c1e20ea47d3a112360f49fde526ca02966e5248550e3a9aca


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

Android Nexus5 Perf

blink_perf.canvas - Benchmark documentation link:
  https://bit.ly/blink-perf-benchmarks

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/16d08d7ae40000

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/16d08d7ae40000

Simplify WebGL dirty notifications. by kbr@chromium.org
https://chromium.googlesource.com/chromium/src/+/a614021bc653b35bef12c80407b2c3b92dad3839
draw-static-webgl-to-hw-accelerated-canvas-2d: 4.715e+04 → 8311 (-3.883e+04)

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

Benchmark documentation link:
  https://bit.ly/blink-perf-benchmarks

Working on this. Hopefully it won't require completely undoing the earlier simplification.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a3216a1cba5057329d0e94e1c6e2d01165d7a85b

commit a3216a1cba5057329d0e94e1c6e2d01165d7a85b
Author: Kenneth Russell <kbr@chromium.org>
Date: Tue Oct 23 17:56:22 2018

Optimize painting WebGL to the canvas again.

Removing the earlier optimization in PaintRenderingResultsToCanvas
induced too large a performance regression for certain cases, such as
drawing static WebGL content to another canvas.

Bug:  897140 
Change-Id: Ibf734ba53f5171f893913a487f74778761123b18
Reviewed-on: https://chromium-review.googlesource.com/c/1295334
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602017}
[modify] https://crrev.com/a3216a1cba5057329d0e94e1c6e2d01165d7a85b/third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc
[modify] https://crrev.com/a3216a1cba5057329d0e94e1c6e2d01165d7a85b/third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.h

This should be fixed by the CL above.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/34ba672a2d4f44364b77c7b688412db06ae0a3fc

commit 34ba672a2d4f44364b77c7b688412db06ae0a3fc
Author: Kenneth Russell <kbr@chromium.org>
Date: Tue Oct 30 19:54:01 2018

Optimize painting WebGL to the canvas again.

Removing the earlier optimization in PaintRenderingResultsToCanvas
induced too large a performance regression for certain cases, such as
drawing static WebGL content to another canvas.

TBR=kbr@chromium.org

(cherry picked from commit a3216a1cba5057329d0e94e1c6e2d01165d7a85b)

Bug:  897140 , 895528
Change-Id: Ibf734ba53f5171f893913a487f74778761123b18
Reviewed-on: https://chromium-review.googlesource.com/c/1295334
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#602017}
Reviewed-on: https://chromium-review.googlesource.com/c/1308668
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#415}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}
[modify] https://crrev.com/34ba672a2d4f44364b77c7b688412db06ae0a3fc/third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc
[modify] https://crrev.com/34ba672a2d4f44364b77c7b688412db06ae0a3fc/third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.h

The following revision refers to this bug: 
https://chromium.googlesource.com/chromium/src.git/+/34ba672a2d4f44364b77c7b688412db06ae0a3fc

Commit: 34ba672a2d4f44364b77c7b688412db06ae0a3fc
Author: kbr@chromium.org
Commiter: kbr@chromium.org
Date: 2018-10-30 19:54:01 +0000 UTC

Optimize painting WebGL to the canvas again.

Removing the earlier optimization in PaintRenderingResultsToCanvas
induced too large a performance regression for certain cases, such as
drawing static WebGL content to another canvas.

TBR=kbr@chromium.org

(cherry picked from commit a3216a1cba5057329d0e94e1c6e2d01165d7a85b)

Bug:  897140 , 895528
Change-Id: Ibf734ba53f5171f893913a487f74778761123b18
Reviewed-on: https://chromium-review.googlesource.com/c/1295334
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#602017}
Reviewed-on: https://chromium-review.googlesource.com/c/1308668
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#415}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}