[DocServer] Annotate code with filename when possible

And I've fixed some nits while I was there also.

BUG=297584
NOTRY=true

Review URL: https://codereview.chromium.org/24376009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225939 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225939
Media Galleries: Remove a useless lock from MediaPathFilter. Replace it with a DCHECK.

Review URL: https://codereview.chromium.org/24876003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225940 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225940
Restore OpenSpecialTypes tests for Files app.

These test do not seem to be flaky anymore. Therefore, reenabling.

TEST=browser_tests: *OpenSpecialTypes/FileManagerBrowserTest.Test*
BUG=252561

Review URL: https://codereview.chromium.org/24962002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225941 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225941