Revert 179987

Revert 179987

Caused memory leak:
Leak_DefinitelyLost
4,196 (1,600 direct, 2,596 indirect) bytes in 4 blocks are definitely lost in loss record 608 of 639
  operator new(unsigned long) (m_replacemalloc/vg_replace_malloc.c:1140)
  IPC::SyncChannel::SyncChannel(IPC::ChannelHandle const&, IPC::Channel::Mode, IPC::Listener*, base::SingleThreadTaskRunner*, bool, base::WaitableEvent*) (ipc/ipc_sync_channel.cc:410)
  (anonymous namespace)::RestrictedDispatchPipeWorker::Run() (ipc/ipc_sync_channel_unittest.cc:1636)
  (anonymous namespace)::Worker::OnStart() (ipc/ipc_sync_channel_unittest.cc:176)
Suppression (error hash=#2A77226DFEFF6041#):
  For more info on using suppressions see http://dev.chromium.org/developers/tree-sheriffs/sheriff-details-chromium/memory-sheriff#TOC-Suppressing-memory-reports
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   fun:_Znw*
   fun:_ZN3IPC11SyncChannelC1ERKNS_13ChannelHandleENS_7Channel4ModeEPNS_8ListenerEPN4base22SingleThreadTaskRunnerEbPNS8_13WaitableEventE
   fun:_ZN12_GLOBAL__N_128RestrictedDispatchPipeWorker3RunEv
   fun:_ZN12_GLOBAL__N_16Worker7OnStartEv
}

15:02:51 memcheck_a
http://build.chromium.org/p/chromium.memory.fyi/builders/Chromium%20OS%20%28valgrind%29%282%29/builds/22101

> Refactor: Simplify WaitableEventWatcher.
> 
> This change uses a callback instead of a delegate for specifying what
> should be called when a WaitableEvent occurs.
> 
> This simplifies the class and gets rid of a workaround internal to the
> class to prevent name collision on "Delegate" inner classes.
> 
> Tested (on linux and windows):
>   ninja -C out/Debug chrome
>   out/Debug/base_unittests --gtest_filter=*WaitableEventWatcherTest*
> 
> BUG=
> 
> 
> Review URL: https://chromiumcodereview.appspot.com/11953112

TBR=teravest@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=179993

[teravest, 2013-01-31 23:15:21]

lgtm