Suppress data race in UI (bug 51890) and remove a suppression for a race fixe...

tools/valgrind/tsan/suppressions.txt

Index: tools/valgrind/tsan/suppressions.txt
===================================================================
--- tools/valgrind/tsan/suppressions.txt	(revision 55717)
+++ tools/valgrind/tsan/suppressions.txt	(working copy)
@@ -14,12 +14,6 @@
 }
 
 {
-  bug_25915
-  ThreadSanitizer:Race
-  fun:*browser_sync*BookmarkModelWorker*
-}
-
-{
   bug_37496
   ThreadSanitizer:Race
   ...
@@ -38,6 +32,22 @@
   fun:*media*PipelineImpl*GetCurrentTime*
 }
 
+{
+  bug_51890a
+  ThreadSanitizer:Race
+  ...
+  fun:history::TopSites::GenerateCanonicalURLs*
+  fun:history::TopSites::StoreMostVisited*
+}
+
+{
+  bug_51890b
+  ThreadSanitizer:Race
+  ...
+  fun:history::TopSites::SetPageThumbnail*
+  fun:TabContents::UpdateThumbnail*
+}
+
 ############################
 # Real races in third_party
 {