[MemSheriff] Allow exclusion of symbols

Occasionally, the logs get swamped with leaks from a specific module.
To allow seeing suppressions not related to that, this CL allows
'waterfall match' to exclude any reports that contain a specified
list of symbols

BUG=none

Review URL: https://codereview.chromium.org/63073004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233578 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233578
AppCache: unconditionally allow chrome-devtools scheme for processing.

BUG=315167
R=michaeln@chromium.org

Review URL: https://codereview.chromium.org/58833008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233579 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233579