Fix memory leak in SyncableExtensionSettingsStorage.

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 # running overnight and removing outdated bugs/suppressions.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 4637 matching lines @@
 {
    bug_97511_c
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN26ExtensionSettingsUIWrapper4Core16InitOnFileThreadERK8FilePath
    fun:_ZN4base8internal8Invoker2ILb0ENS0_15InvokerStorage2IMN26ExtensionSettingsUIWrapper4CoreEFvRK8FilePathEPS4_S5_EES9_E8DoInvokeEPNS0_18InvokerStorageBaseE
    fun:_ZNK4base8CallbackIFvvEE3RunEv
    ...
    fun:_ZN*Extension*Test*
 }
-{
-   bug_97511_d
-   Memcheck:Leak
-   fun:_Znw*
-   ...
-   fun:_ZNK4base15DictionaryValue8DeepCopyEv
-   fun:_ZN32SyncableExtensionSettingsStorage30OverwriteLocalSettingsWithSyncERKN4base15DictionaryValueES3_
-   fun:_ZN32SyncableExtensionSettingsStorage12StartSyncingERKN4base15DictionaryValueEP19SyncChangeProcessor
-   fun:_ZN17ExtensionSettings24MergeDataAndStartSyncingEN8syncable9ModelTypeERKSt6vectorI8SyncDataSaIS3_EEP19SyncChangeProcessor
-   fun:_ZN58ExtensionSettingsSyncTest_InSyncDataDoesNotInvokeSync_Test8TestBodyEv
-}
 
 #-----------------------------------------------------------------------
 # 4. These only occur on our Google workstations
 {
    bug_todo_freeres
    Memcheck:Free
    fun:free
    fun:__libc_freeres
    fun:_vgnU_freeres
    fun:_Exit
@@ skipping 10 matching lines @@
 }
 {
    bug_todo_getdelim2
    Memcheck:Leak
    fun:malloc
    fun:getdelim
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
 }