Parameterize TaskRunner used by ui::Compositor

ui/compositor/test/test_compositor_host_mac.mm

Index: ui/compositor/test/test_compositor_host_mac.mm
diff --git a/ui/compositor/test/test_compositor_host_mac.mm b/ui/compositor/test/test_compositor_host_mac.mm
index 96599670fd71510f1641d3a644c6a900c548a8d5..8d533d08d41a243198fecab47b8ef1f8dc24d42a 100644
--- a/ui/compositor/test/test_compositor_host_mac.mm
+++ b/ui/compositor/test/test_compositor_host_mac.mm
@@ -13,6 +13,7 @@
 #include "base/compiler_specific.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/message_loop/message_loop.h"
 #include "ui/compositor/compositor.h"
 #include "ui/gfx/rect.h"
 
@@ -130,7 +131,9 @@ void TestCompositorHostMac::Show() {
                               defer:NO];
   base::scoped_nsobject<AcceleratedTestView> view(
       [[AcceleratedTestView alloc] init]);
-  compositor_.reset(new ui::Compositor(view, context_factory_));
+  compositor_.reset(new ui::Compositor(view,
+                                       context_factory_,
+                                       base::MessageLoopProxy::current()));
   compositor_->SetScaleAndSize(1.0f, bounds_.size());
   [view setCompositor:compositor_.get()];
   [window_ setContentView:view];