Implementation of PostTaskAndReply() in MessageLoopProxy and BrowserThread.

tools/valgrind/memcheck/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 # running overnight and removing outdated bugs/suppressions.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 727 matching lines @@
    fun:_ZN4base43ToolsSanityTest_AccessesToMallocMemory_Test8TestBodyEv
 }
 {
    Memcheck sanity test 15 (new/read uninit).
    Memcheck:Cond
    fun:*ReadUninitializedValue*
    fun:*MakeSomeErrors*
    fun:_ZN4base40ToolsSanityTest_AccessesToNewMemory_Test8TestBodyEv
 }
 {
+   bug_86301 This test explicitly verifies PostTaskAndReply leaks the task if the originating MessageLoop has been deleted.
+   Memcheck:Leak
+   fun:_Znw*
+   fun:_ZN4base16MessageLoopProxy16PostTaskAndReplyERKN15tracked_objects8LocationERKNS_8CallbackIFvvEEES9_
+   fun:_ZN4base12_GLOBAL__N_169MessageLoopProxyTest_PostTaskAndReply_DeadReplyLoopDoesNotDelete_Test8TestBodyEv
+}
+{
    logging::InitLogging never frees filename. It would be hard to free properly.
    Memcheck:Leak
    ...
    fun:_ZN7logging11InitLoggingEPKcNS_18LoggingDestinationENS_15LogLockingStateENS_20OldFileDeletionStateE
 }
 {
    Linux tests don't bother to undo net::TestServer::LoadTestRootCert().
    Memcheck:Leak
    ...
    fun:_ZN3net10TestServer16LoadTestRootCertEv
@@ skipping 4571 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
 }