Add new heapchecl suppression for MediaGalleriesPreferencesTests.

BUG=141322
TBR=thestig@chromium.org
NOTRY=TRUE


Review URL: https://chromiumcodereview.appspot.com/10826221

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150754 0039d316-1c4b-4281-b951-d872f2087c98

tools/heapcheck/suppressions.txt

@@ -1577,3 +1577,9 @@
    fun:MessageLoop::MessageLoop
    fun:ExtensionUpdaterTest
 }
+{
+   bug_141322
+   Heapcheck:Leak
+   fun:MessageLoop::MessageLoop
+   fun:MediaGalleriesPreferencesTest
+}