Remove memory error suppressions for leaks caused by PostTaskAndReply in ImportantFileWriter.

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 # running overnight and removing outdated bugs/suppressions.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 6386 matching lines @@
 {
    bug_371860
    Memcheck:Leak
    fun:_Znw*
    ...
    fun:_ZN8feedback20FeedbackUploaderTestC1Ev
    fun:_ZN8feedback*FeedbackUploaderTest*
    fun:_ZN7testing8internal15TestFactoryImplIN8feedback*
 }
 {
-   bug_371974
-   Memcheck:Leak
-   fun:_Znw*
-   fun:_ZN4base8internal20PostTaskAndReplyImpl16PostTaskAndReplyERKN15tracked_objects8LocationERKNS_8CallbackIFvvEEESA_
-   fun:_ZN4base10TaskRunner16PostTaskAndReplyERKN15tracked_objects8LocationERKNS_8CallbackIFvvEEES9_
-   fun:_ZN4base26PostTaskAndReplyWithResultIbbEEbPNS_10TaskRunnerERKN15tracked_objects8LocationERKNS_8CallbackIFT_vEEERKNS7_IFvT0_EEE
-   fun:_ZN4base19ImportantFileWriter8WriteNowERKSs
-}
-{
    bug_372487_a
    Memcheck:Leak
    fun:_Znw*
    ...
    fun:_ZN4mojo10BindToPipeIN7content19MojoApplicationHost9ShellImplEEEPT_S5_NS_16ScopedHandleBaseINS_17MessagePipeHandleEEEP15MojoAsyncWaiter
    fun:_ZN7content19MojoApplicationHost4InitEv
    fun:_ZN7content21RenderProcessHostImpl4InitEv
    fun:_ZN7content18RenderViewHostImpl16CreateRenderViewERKSbItN4base20string16_char_traitsESaItEEiib
    fun:_ZN7content15WebContentsImpl32CreateRenderViewForRenderManagerEPNS_14RenderViewHostEiPNS_26CrossProcessFrameConnectorE
    fun:_ZN7content22RenderFrameHostManager14InitRenderViewEPNS_14RenderViewHostEi
@@ skipping 89 matching lines @@
    ...
    fun:_ZN7WebCore18ModulesInitializer20registerEventFactoryEv
    fun:_ZN7WebCore15CoreInitializer4initEv
    fun:_ZN5blink19initializeWithoutV8EPNS_8PlatformE
    fun:_ZN5blink10initializeEPNS_8PlatformE
    fun:_ZN7content25TestWebKitPlatformSupportC2Ev
    fun:_ZN7content25TestWebKitPlatformSupportC1Ev
    fun:_ZN7content17UnitTestTestSuiteC2EPN4base9TestSuiteE
    fun:_ZN7content17UnitTestTestSuiteC1EPN4base9TestSuiteE
 }