Remove the last Histogram suppression

Ignores look like to be sufficient to remove any reports.

BUG=62694
TBR=thakis
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/12091106

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@180127 0039d316-1c4b-4281-b951-d872f2087c98

tools/valgrind/tsan/suppressions.txt

@@ -353,14 +353,6 @@
   fun:tracked_objects::Births::*Birth*
 }
 
-{
-   benign race on Histogram::Add - TO BE REMOVED SOON
-   ThreadSanitizer:Race
-   ...
-   fun:base::SampleVector::Accumulate
-   fun:base::Histogram::Add
-}
-
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 ############################
 # Real races in Chromium