Valgrind/Heapchecker: Add a new suppression for a JsSyncManagerObserverTest leak.

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 # running overnight and removing outdated bugs/suppressions.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 5730 matching lines @@
    fun:_ZN3WTF14deleteOwnedPtrIN7WebCore22WorkerScriptControllerEEEvPT_
    fun:_ZN3WTF6OwnPtrIN7WebCore22WorkerScriptControllerEE5clearEv
    fun:_ZN7WebCore13WorkerContext11clearScriptEv
    fun:_ZN7WebCore30WorkerThreadShutdownFinishTask11performTaskEPNS_22ScriptExecutionContextE
    fun:_ZN7WebCore13WorkerRunLoop4Task11performTaskERKS0_PNS_22ScriptExecutionContextE
    fun:_ZN7WebCore13WorkerRunLoop9runInModeEPNS_13WorkerContextERKNS_13ModePredicateENS0_8WaitModeE
    fun:_ZN7WebCore13WorkerRunLoop3runEPNS_13WorkerContextE
    fun:_ZN7WebCore12WorkerThread12runEventLoopEv
    fun:_ZN7WebCore21DedicatedWorkerThread12runEventLoopEv
 }
+{
+   bug_139635
+   Memcheck:Leak
+   fun:_Znw*
+   fun:_ZN6syncer21JsSyncManagerObserver24OnInitializationCompleteERKNS_10WeakHandleINS_9JsBackendEEEbNS_7EnumSetINS_9ModelTypeELS7_2ELS7_16EEE
+   fun:_ZN6syncer12_GLOBAL__N_155JsSyncManagerObserverTest_OnInitializationComplete_Test8TestBodyEv
+}
 
 #-----------------------------------------------------------------------
 # 4. These only occur on our Google workstations
 
 {
    bug_todo_getdelim
    Memcheck:Leak
    fun:malloc
    fun:getdelim
    ...
    fun:call_init
    fun:_dl_init
 }
 {
    bug_todo_getdelim2
    Memcheck:Leak
    fun:malloc
    fun:getdelim
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
 }
 {
    bug_todo_grep
    Memcheck:Leak
    fun:malloc
    obj:/bin/grep
    obj:/bin/grep
 }