Fix memory leaks in AsynchronousPolicyProvider.

tools/valgrind/memcheck/suppressions_mac.txt

 # There are three kinds of suppressions in this file:
 # 1. Third party stuff we have no control over.
 #
 # 2. Intentional unit test errors, 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.
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 1155 matching lines @@
    bug_65940
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN3IPC11SyncChannelC2ERKNS_13ChannelHandleENS_7Channel4ModeEPNS4_8ListenerEP11MessageLoopbPN4base13WaitableEventE
    fun:_ZN3IPC11SyncChannelC1ERKNS_13ChannelHandleENS_7Channel4ModeEPNS4_8ListenerEP11MessageLoopbPN4base13WaitableEventE
    fun:_ZN11ChildThread4InitEv
    fun:_ZN11ChildThreadC2Ev
    fun:_ZN13UtilityThreadC2Ev
    fun:_ZN13UtilityThreadC1Ev
 }
-{
-   bug_66102
-   Memcheck:Leak
-   fun:_Znw*
-   ...
-   fun:_ZN6policy21FileBasedPolicyLoader11InitWatcherEv
-   ...
-   fun:_ZN54PrefValueStorePolicyRefreshTest_TestPolicyRefresh_Test8TestBodyEv
-}