aura: don't append --viz in AuraTestHelper

Setting --viz in AuraTestHelper means we can't run tests as they would
run when --mus is specified on the command line. If this is necessary,
it's better to push to the testsuite.

BUG=786453
TEST=none

Change-Id: I4b6f6b9685f16abdcf4c8e69347239368ad9a6b3
Reviewed-on: https://chromium-review.googlesource.com/806797Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521507}

ui/aura/test/aura_test_helper.cc

@@ -31,7 +31,6 @@
 #include "ui/base/ime/input_method_factory.h"
 #include "ui/base/ime/input_method_initializer.h"
 #include "ui/base/platform_window_defaults.h"
-#include "ui/base/ui_base_switches.h"
 #include "ui/compositor/compositor.h"
 #include "ui/compositor/layer_animator.h"
 #include "ui/compositor/scoped_animation_duration_scale_mode.h"
@@ -121,10 +120,6 @@ void AuraTestHelper::SetUp(ui::ContextFactory* context_factory,
   capture_client_ = std::make_unique<client::DefaultCaptureClient>();
   const Env::Mode env_mode =
       (mode_ == Mode::LOCAL) ? Env::Mode::LOCAL : Env::Mode::MUS;
-  if (env_mode == Env::Mode::MUS) {
-    base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
-        switches::kMus, switches::kMusHostVizValue);
-  }
 
   if (mode_ == Mode::MUS_CREATE_WINDOW_TREE_CLIENT)
     InitWindowTreeClient();