content: Add an overridable task runner to ChildThreadImpl

content/renderer/render_thread_impl_browsertest.cc

Index: content/renderer/render_thread_impl_browsertest.cc
diff --git a/content/renderer/render_thread_impl_browsertest.cc b/content/renderer/render_thread_impl_browsertest.cc
index 2017e573ad9a40882d1f8fbcb774e0632ad75a47..fee185757a2a61c418d592720d3356d1da78e4cb 100644
--- a/content/renderer/render_thread_impl_browsertest.cc
+++ b/content/renderer/render_thread_impl_browsertest.cc
@@ -16,6 +16,7 @@
 #include "content/public/renderer/content_renderer_client.h"
 #include "content/renderer/render_process_impl.h"
 #include "content/renderer/render_thread_impl.h"
+#include "content/renderer/scheduler/renderer_scheduler.h"
 #include "content/test/mock_render_process.h"
 #include "content/test/render_thread_impl_browser_test_ipc_helper.h"
 #include "gpu/GLES2/gl2extchromium.h"
@@ -89,7 +90,8 @@ class RenderThreadImplForTest : public RenderThreadImpl {
  public:
   RenderThreadImplForTest(const std::string& channel_id,
                           scoped_refptr<TestTaskCounter> test_task_counter)
-      : RenderThreadImpl(channel_id), test_task_counter_(test_task_counter) {}
+      : RenderThreadImpl(channel_id, RendererScheduler::Create()),
+        test_task_counter_(test_task_counter) {}
 
   ~RenderThreadImplForTest() override {}