Remove all remaining traces of MessageLoopProxy.

chrome/browser/apps/app_shim/app_shim_host_mac.cc

Index: chrome/browser/apps/app_shim/app_shim_host_mac.cc
diff --git a/chrome/browser/apps/app_shim/app_shim_host_mac.cc b/chrome/browser/apps/app_shim/app_shim_host_mac.cc
index 6ce706eba279fb95fe84bb5154bd53ec2c820c62..edcce64de6ef6073d4e4529fa3429dba6e4453bf 100644
--- a/chrome/browser/apps/app_shim/app_shim_host_mac.cc
+++ b/chrome/browser/apps/app_shim/app_shim_host_mac.cc
@@ -25,11 +25,9 @@ void AppShimHost::ServeChannel(const IPC::ChannelHandle& handle) {
   DCHECK(CalledOnValidThread());
   DCHECK(!channel_.get());
   channel_ = IPC::ChannelProxy::Create(
-      handle,
-      IPC::Channel::MODE_SERVER,
-      this,
-      content::BrowserThread::GetMessageLoopProxyForThread(
-          content::BrowserThread::IO).get());
+      handle, IPC::Channel::MODE_SERVER, this,
+      content::BrowserThread::GetTaskRunnerForThread(content::BrowserThread::IO)
+          .get());
 }
 
 base::FilePath AppShimHost::GetProfilePath() const {