Remove some media-related tsan suppressions that are no longer valid.

The code paths have been different for quite some time without any new suppressions filed. In addition to that, I've landed a few patches that improve the thread safety of code in question!

BUG=46642,107181
TBR=timurrrr

Review URL: https://chromiumcodereview.appspot.com/10830250

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150903 0039d316-1c4b-4281-b951-d872f2087c98

tools/valgrind/tsan/suppressions.txt

@@ -431,18 +431,6 @@
   fun:ChildProcessLauncher::Context::LaunchInternal*
 }
 
-{
-  bug_46642a
-  ThreadSanitizer:Race
-  fun:*media*Pipeline*InitializeTask*
-}
-
-{
-  bug_46642b
-  ThreadSanitizer:Race
-  fun:*media*Pipeline*GetCurrentTime*
-}
-
 {
   bug_57266a
   ThreadSanitizer:Race
@@ -757,26 +745,6 @@
   fun:ChildThread::OnSetProfilerStatus
   fun:DispatchToMethod
 }
-{
-  bug_107181a
-  ThreadSanitizer:Race
-  ...
-  fun:media::AudioRendererBase::SetPlaybackRate
-  fun:AudioRendererImpl::SetPlaybackRate
-  fun:media::CompositeFilter::SetPlaybackRate
-  fun:media::Pipeline::PlaybackRateChangedTask
-  ...
-  fun:base::internal::RunnableAdapter::Run
-}
-{
-  bug_107181b
-  ThreadSanitizer:Race
-  fun:media::AudioRendererAlgorithmBase::playback_rate
-  fun:media::AudioRendererBase::GetPlaybackRate
-  fun:AudioRendererImpl::Render
-  fun:AudioDevice::FireRenderCallback
-  fun:AudioDevice::Run
-}
 {
    bug_107903_a
    ThreadSanitizer:Race