[arc] Don't bring up ScopedIPCSupport for unit tests

This is flakily crashing because it doesn't shut down
synchronously between tests, or so it seems.

Doesn't matter though because it's no longer necessary
for Mojo unless doing actual IPC.

R=lhchavez@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/1639023003

Cr-Commit-Position: refs/heads/master@{#371663}

components/arc/arc_bridge_service_unittest.cc

@@ -84,7 +84,6 @@ class ArcBridgeTest : public testing::Test, public ArcBridgeService::Observer {
     ready_ = false;
     state_ = ArcBridgeService::State::STOPPED;
 
-    ipc_support_.reset(new IPC::ScopedIPCSupport(message_loop_.task_runner()));
     instance_.reset(new FakeArcBridgeInstance());
     service_.reset(new ArcBridgeServiceImpl(
         make_scoped_ptr(new FakeArcBridgeBootstrap(instance_.get()))));
@@ -96,14 +95,12 @@ class ArcBridgeTest : public testing::Test, public ArcBridgeService::Observer {
     service_->RemoveObserver(this);
     instance_.reset();
     service_.reset();
-    ipc_support_.reset();
 
     chromeos::DBusThreadManager::Shutdown();
   }
 
   bool ready_;
   ArcBridgeService::State state_;
-  scoped_ptr<IPC::ScopedIPCSupport> ipc_support_;
   base::MessageLoopForUI message_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcBridgeTest);