[SyncFS] Move FROM_HEREs in SyncTaskManager to its client

Move location marker to make logs meaningful.

BUG=344769

Review URL: https://codereview.chromium.org/190243003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255882 0039d316-1c4b-4281-b951-d872f2087c98
Adding a Endure regression test to catch gmail memory issues (crbug.com/345702).

Review URL: https://codereview.chromium.org/187173002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255883 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255883