Issue 865738 has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/96e0143b8d5d5d4ec509231ab631c79a32f14cc3

commit 96e0143b8d5d5d4ec509231ab631c79a32f14cc3
Author: Tommy Steimel <steimel@chromium.org>
Date: Fri Jul 27 17:00:46 2018

[Media Intent Handler] Hide CustomTabActivity's menu button when empty

This CL adds logic to CustomTabActivity's toolbar initialization to
remove the menu button when it is empty. This happens when the UI is a
media viewer (which disables all default menu items) and when the media
is opened via the MediaLauncherActivity (which doesn't add any custom
menu items). In addition to removing the menu button, the margin on the
custom action button bar is removed in order to shift the custom
buttons over to where the menu button was.

Bug:  865103 
Change-Id: I19fa270bf30d80d711a0b288b97c9edde79bad2f
Reviewed-on: https://chromium-review.googlesource.com/1149019
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578678}
[modify] https://crrev.com/96e0143b8d5d5d4ec509231ab631c79a32f14cc3/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabActivity.java
[modify] https://crrev.com/96e0143b8d5d5d4ec509231ab631c79a32f14cc3/chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbar.java
[modify] https://crrev.com/96e0143b8d5d5d4ec509231ab631c79a32f14cc3/chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarLayout.java

Your change meets the bar and is auto-approved for M69. Please go ahead and merge the CL to branch 3497 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), kariahda@(iOS), cindyb@(ChromeOS), govind@(Desktop)

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

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/13508678a183a73cb0aedf99f45b2da66344d8ff

commit 13508678a183a73cb0aedf99f45b2da66344d8ff
Author: Mounir Lamouri <mlamouri@chromium.org>
Date: Mon Jul 30 16:01:18 2018

[Media Intent Handler] Hide CustomTabActivity's menu button when empty

This CL adds logic to CustomTabActivity's toolbar initialization to
remove the menu button when it is empty. This happens when the UI is a
media viewer (which disables all default menu items) and when the media
is opened via the MediaLauncherActivity (which doesn't add any custom
menu items). In addition to removing the menu button, the margin on the
custom action button bar is removed in order to shift the custom
buttons over to where the menu button was.

(cherry picked from commit 96e0143b8d5d5d4ec509231ab631c79a32f14cc3)

Bug:  865103 
Change-Id: I19fa270bf30d80d711a0b288b97c9edde79bad2f
Reviewed-on: https://chromium-review.googlesource.com/1149019
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#578678}
Reviewed-on: https://chromium-review.googlesource.com/1155147
Cr-Commit-Position: refs/branch-heads/3497@{#208}
Cr-Branched-From: 271eaf50594eb818c9295dc78d364aea18c82ea8-refs/heads/master@{#576753}
[modify] https://crrev.com/13508678a183a73cb0aedf99f45b2da66344d8ff/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabActivity.java
[modify] https://crrev.com/13508678a183a73cb0aedf99f45b2da66344d8ff/chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbar.java
[modify] https://crrev.com/13508678a183a73cb0aedf99f45b2da66344d8ff/chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarLayout.java

Verified in M69-69.0.3497.24 build. Removed the empty three-dot menu.