Add a |scope| argument to TRACE_EVENT_INSTANT* and require its presence.

ui/surface/accelerated_surface_win.cc

Index: ui/surface/accelerated_surface_win.cc
diff --git a/ui/surface/accelerated_surface_win.cc b/ui/surface/accelerated_surface_win.cc
index 3d88f701866896adb2f54a673e1b6e2aee3ebe9d..92d81d26f81a95efe34c3ba1a9efbb70b611ecd9 100644
--- a/ui/surface/accelerated_surface_win.cc
+++ b/ui/surface/accelerated_surface_win.cc
@@ -775,7 +775,8 @@ void AcceleratedPresenter::DoPresentAndAcknowledge(
     hr = swap_chain_->Present(&rect, &rect, window_, NULL, 0);
 
     // For latency_tests.cc:
-    UNSHIPPED_TRACE_EVENT_INSTANT0("test_gpu", "CompositorSwapBuffersComplete");
+    UNSHIPPED_TRACE_EVENT_INSTANT0("test_gpu", "CompositorSwapBuffersComplete",
+                                   TRACE_EVENT_SCOPE_THREAD);
 
     if (FAILED(hr)) {
       if (present_thread_->IsDeviceLost())
@@ -954,7 +955,8 @@ void AcceleratedPresenter::PresentWithGDI(HDC dc) {
   system_surface->UnlockRect();
 
   // For latency_tests.cc:
-  UNSHIPPED_TRACE_EVENT_INSTANT0("test_gpu", "CompositorSwapBuffersComplete");
+  UNSHIPPED_TRACE_EVENT_INSTANT0("test_gpu", "CompositorSwapBuffersComplete",
+                                 TRACE_EVENT_SCOPE_THREAD);
 }
 
 gfx::Size AcceleratedPresenter::GetWindowSize() {