Please find logs and video  @ http://go/chrome-androidlogs1/6/694986

Cannot provide bisect info as issue is not reproducible in the public build

tedchoc@, Can you please help us in looking in to this bug, Thanks!

I suspect this is the same as:
https://bugs.chromium.org/p/chromium/issues/detail?id=690111

To me, it seems like "something" broke with the fade logic, but I don't know where that could be.  Adding mdjones@ and aelias@ to glance at the regression range to see if anything jumps out.

It does repro on chrome_public_apk, contrary to the claim on #2.  I exactly bisected to http://crrev.com/442359 "The great shader refactor: Merge all vertex shaders"

 Issue 690111  has been merged into this issue.

As I recall, this effect is implemented by creating a small UIResource for the right edge of the title text, and then using UIResourceLayer::SetVertexOpacity on it.

FWIW, it's DecorationTitle::layer_fade_.

Just a reminder that M57 Stable launch is coming very soon.  Since this is a release blocker, please get your fix in asap so it gets some soak time in Beta.  Thanks!

Thanks for the analysis! I'll check the vertex opacity source to see if I missed something.

Hmm, that patch has
-      v_alpha = opacity[int(a_index)]; 
And
+    SRC("v_alpha = opacity[quad_index];");

Oops. I'll put up a patch once I add a unit test.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8558df98469ef25bcd685bd9f9b0dc080ad2dc5b

commit 8558df98469ef25bcd685bd9f9b0dc080ad2dc5b
Author: ccameron <ccameron@chromium.org>
Date: Wed Mar 01 06:31:11 2017

cc: Fix vertex opacity shaders

Fix a typo that indexed by quad, not vertex.

Add a pixel test to prevent regressions.

BUG= 694986 
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2724563003
Cr-Commit-Position: refs/heads/master@{#453865}

[modify] https://crrev.com/8558df98469ef25bcd685bd9f9b0dc080ad2dc5b/cc/output/renderer_pixeltest.cc
[modify] https://crrev.com/8558df98469ef25bcd685bd9f9b0dc080ad2dc5b/cc/output/shader.cc
[add] https://crrev.com/8558df98469ef25bcd685bd9f9b0dc080ad2dc5b/cc/test/data/green_alpha_vertex_opacity.png

Your change meets the bar and is auto-approved for M57. Please go ahead and merge the CL to branch 2987 manually. Please contact milestone owner if you have questions.
Owners: amineer@(clank), cmasso@(bling), ketakid@(cros), govind@(desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

M57 Stable launch is VERY soon.  Since this is a release blocker, please get your fix merged into the release branch (2987) ASAP.  Thanks!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/10c39d4c0e6e423f01b86ef69b5966dea4e3c682

commit 10c39d4c0e6e423f01b86ef69b5966dea4e3c682
Author: Christopher Cameron <ccameron@chromium.org>
Date: Thu Mar 02 19:45:26 2017

cc: Fix vertex opacity shaders

Fix a typo that indexed by quad, not vertex.

Add a pixel test to prevent regressions.

BUG= 694986 
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2724563003
Cr-Commit-Position: refs/heads/master@{#453865}
(cherry picked from commit 8558df98469ef25bcd685bd9f9b0dc080ad2dc5b)

Review-Url: https://codereview.chromium.org/2724183003 .
Cr-Commit-Position: refs/branch-heads/2987@{#740}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}

[modify] https://crrev.com/10c39d4c0e6e423f01b86ef69b5966dea4e3c682/cc/output/renderer_pixeltest.cc
[modify] https://crrev.com/10c39d4c0e6e423f01b86ef69b5966dea4e3c682/cc/output/shader.cc
[add] https://crrev.com/10c39d4c0e6e423f01b86ef69b5966dea4e3c682/cc/test/data/green_alpha_vertex_opacity.png

This issue is fixed on latest M57-57.0.2987.91 and M58-58.0.3028.4