Revert "Make SingleThreadProxy a SchedulerClient"

content/shell/renderer/test_runner/web_test_proxy.cc

Index: content/shell/renderer/test_runner/web_test_proxy.cc
diff --git a/content/shell/renderer/test_runner/web_test_proxy.cc b/content/shell/renderer/test_runner/web_test_proxy.cc
index 18086de32ee8f1eb6b975bb02ad542c083b682a3..7e36976482f629bd7a9950aa94f066cb599a3137 100644
--- a/content/shell/renderer/test_runner/web_test_proxy.cc
+++ b/content/shell/renderer/test_runner/web_test_proxy.cc
@@ -7,11 +7,9 @@
 #include <cctype>
 
 #include "base/callback_helpers.h"
-#include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
-#include "content/public/common/content_switches.h"
 #include "content/shell/renderer/test_runner/TestPlugin.h"
 #include "content/shell/renderer/test_runner/WebTestDelegate.h"
 #include "content/shell/renderer/test_runner/WebTestInterfaces.h"
@@ -315,10 +313,6 @@ WebTestProxyBase::WebTestProxyBase()
       web_widget_(NULL),
       spellcheck_(new SpellCheckClient(this)),
       chooser_count_(0) {
-  // TODO(enne): using the scheduler introduces additional composite steps
-  // that create flakiness.  This should go away eventually.
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kDisableSingleThreadProxyScheduler);
   Reset();
 }