Hook up ui::Compositor to Display's BeginFrameSource

cc/test/pixel_test.cc

Index: cc/test/pixel_test.cc
diff --git a/cc/test/pixel_test.cc b/cc/test/pixel_test.cc
index 58e556437b1b07a1e5fc719f248299864b80736d..cdd844b6b19d17ad10487f72fbb03ae12cea5ab9 100644
--- a/cc/test/pixel_test.cc
+++ b/cc/test/pixel_test.cc
@@ -18,6 +18,7 @@
 #include "cc/output/texture_mailbox_deleter.h"
 #include "cc/raster/tile_task_worker_pool.h"
 #include "cc/resources/resource_provider.h"
+#include "cc/scheduler/begin_frame_source.h"
 #include "cc/test/fake_output_surface_client.h"
 #include "cc/test/paths.h"
 #include "cc/test/pixel_test_output_surface.h"
@@ -126,7 +127,7 @@ void PixelTest::SetUpGLRenderer(bool use_skia_gpu_backend,
 
   output_surface_.reset(new PixelTestOutputSurface(
       new TestInProcessContextProvider, new TestInProcessContextProvider,
-      flipped_output_surface));
+      flipped_output_surface, nullptr));
   output_surface_->BindToClient(output_surface_client_.get());
 
   shared_bitmap_manager_.reset(new TestSharedBitmapManager);
@@ -170,7 +171,7 @@ void PixelTest::EnableExternalStencilTest() {
 
 void PixelTest::SetUpSoftwareRenderer() {
   scoped_ptr<SoftwareOutputDevice> device(new PixelTestSoftwareOutputDevice());
-  output_surface_.reset(new PixelTestOutputSurface(std::move(device)));
+  output_surface_.reset(new PixelTestOutputSurface(std::move(device), nullptr));
   output_surface_->BindToClient(output_surface_client_.get());
   shared_bitmap_manager_.reset(new TestSharedBitmapManager());
   resource_provider_ = ResourceProvider::Create(