Leaks found in PrefValueStoreTest tests

tools/heapcheck/suppressions.txt

 # There are three 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 # running overnight and removing outdated bugs/suppressions.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 927 matching lines @@
    fun:sync_notifier::ChromeSystemResources::MakeTaskToPost
    fun:sync_notifier::ChromeSystemResources::Schedule*
    fun:sync_notifier::::ChromeSystemResourcesTest::ScheduleShouldNotRun
 }
 {
    bug_50598
    Heapcheck:Leak
    ...
    fun:safe_browsing::PhishingDOMFeatureExtractorTest::SetUp
 }
+{
+   bug_51176_a
+   Heapcheck:Leak
+   fun:Callback1::Type* NewCallback
+   fun:PrefValueStoreTest_TestPolicyRefresh_Test::TestBody
+}
+{
+   bug_51176_b
+   Heapcheck:Leak
+   fun:Callback1::Type* NewCallback
+   fun:PrefValueStoreTest_TestRefreshPolicyPrefsCompletion_Test::TestBody
+}
+{
+   bug_51176_c
+   Heapcheck:Leak
+   fun:Callback1::Type* NewCallback
+   fun:PrefValueStoreTest_TestConcurrentPolicyRefresh_Test::TestBody
+}