Add another suppression for 252641

tools/valgrind/memcheck/suppressions.txt

 # There are four kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 5051 matching lines @@
 {
    bug_252641_a
    Memcheck:Uninitialized
    fun:pthread_rwlock_init$UNIX2003
    fun:_ZN3re25MutexC2Ev
    fun:_ZN3re25MutexC1Ev
    ...
    fun:_ZN11leveldb_env19ParseMethodAndErrorEPKcPNS_8MethodIDEPi
 }
 {
+   bug_252641_b
+   Memcheck:Uninitialized
+   fun:pthread_rwlock_init$UNIX2003
+   fun:_ZN3re25MutexC2Ev
+   fun:_ZN3re25MutexC1Ev
+   ...
+   fun:_ZN3gpu12_GLOBAL__N_114StringMismatchERKSsS2_
+}
+{
    bug_253797
    Memcheck:Uninitialized
    fun:_ZNSt11char_traitsIcE6lengthEPKc
    fun:_ZN4base8internal17StringPieceDetail*
    fun:_ZN4base16BasicStringPieceISsEC1EPKc
    fun:_ZN8autofill22AutofillQueryXmlParser13CharacterDataEPN4buzz15XmlParseContextEPKci
    fun:_ZN4buzz9XmlParser18ExpatCharacterDataEPKci
    fun:_ZN4buzzL21CharacterDataCallbackEPvPKci
    obj:*libexpat.so*
    obj:*libexpat.so*
@@ skipping 1172 matching lines @@
 }
 {
    bug_400547
    Memcheck:Uninitialized
    fun:_ZNK5blink22GraphicsLayerDebugInfo17appendOwnerNodeIdEPNS_10JSONObjectE
    fun:_ZNK5blink22GraphicsLayerDebugInfo19appendAsTraceFormatEPNS_9WebStringE
    fun:_ZNK7content15TracedDebugInfo19AppendAsTraceFormatEPSs
    fun:_ZNK2cc9LayerImpl11AsValueIntoEPN4base5debug11TracedValueE
    fun:_ZNK2cc*LayerImpl11AsValueIntoEPN4base5debug11TracedValueE
 }