[Automated comment] Less than 2 weeks to go before stable on M50, manual review required.

Merge approved for M50 (branch 2661). Pls go ahead merge.

Please merge your change to M50 branch 2661 by 5:00 PM PST on April 8th,Friday to make into the desktop Stable final build cut. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e66018a471cac336485b8a733f73b78376e383f6

commit e66018a471cac336485b8a733f73b78376e383f6
Author: Georges Khalil <georgesak@chromium.org>
Date: Fri Apr 08 14:59:02 2016

[TabManager] [Merge M50] Protect tabs opened in background.

BUG= 600706 , 580690 ,551995

Review URL: https://codereview.chromium.org/1826333002

Cr-Commit-Position: refs/heads/master@{#383727}
(cherry picked from commit 0b7fc1ccb05b5fec8cbb4f4e6f79228f7aeb0d8e)

R=chrisha@chromium.org

Review URL: https://codereview.chromium.org/1867343002 .

Cr-Commit-Position: refs/branch-heads/2661@{#528}
Cr-Branched-From: ef6f6ae5e4c96622286b563658d5cd62a6cf1197-refs/heads/master@{#378081}

[modify] https://crrev.com/e66018a471cac336485b8a733f73b78376e383f6/chrome/browser/memory/tab_manager.cc
[modify] https://crrev.com/e66018a471cac336485b8a733f73b78376e383f6/chrome/browser/memory/tab_manager.h
[modify] https://crrev.com/e66018a471cac336485b8a733f73b78376e383f6/chrome/browser/memory/tab_manager_browsertest.cc

georgesak@ : Could you please provide any steps to verify it from Test Engg team.

- Test must be done on Windows
- Append the following command line options:
  --enable-automatic-tab-discarding --memory-pressure-thresholds-mb=65536,65536
- Open a link in the background (middle click a link or right click then choose Open link in new tab). The background tab must not be activated throughout this test until the last step
- Wait a minute
- Open chrome://discards in a new tab
- Background tab must not be shown as discarded
- Wait ~15 mins and reload chrome://discards
- The background tab should now show as discarded
- Activate the background tab, it should reload (confirming it was discarded)