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

content/browser/renderer_host/compositing_iosurface_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/compositing_iosurface_mac.h"
 
 #include <OpenGL/CGLRenderers.h>
 #include <OpenGL/OpenGL.h>
 #include <vector>
 
@@ skipping 458 matching lines @@
     if (frame_subscriber->ShouldCaptureFrame(&frame, &callback)) {
       copy_done_callback = CopyToVideoFrameWithinContext(
           gfx::Rect(io_surface_size_), scale_factor, true, frame,
           base::Bind(callback, base::Time::Now()));
     }
   }
 
   CGLFlushDrawable(cglContext_);
 
   // For latency_tests.cc:
-  UNSHIPPED_TRACE_EVENT_INSTANT0("test_gpu", "CompositorSwapBuffersComplete");
+  UNSHIPPED_TRACE_EVENT_INSTANT0("test_gpu", "CompositorSwapBuffersComplete",
+                                 TRACE_EVENT_SCOPE_THREAD);
 
   // Try to finish previous copy requests after flush to get better pipelining.
   std::vector<base::Closure> copy_done_callbacks;
   FinishAllCopiesWithinContext(&copy_done_callbacks);
 
   CGLSetCurrentContext(0);
 
   if (!copy_done_callback.is_null())
     copy_done_callbacks.push_back(copy_done_callback);
   for (size_t i = 0; i < copy_done_callbacks.size(); ++i)
@@ skipping 518 matching lines @@
 }
 
 gfx::Rect CompositingIOSurfaceMac::IntersectWithIOSurface(
     const gfx::Rect& rect, float scale_factor) const {
   return gfx::IntersectRects(rect,
       gfx::ToEnclosingRect(gfx::ScaleRect(gfx::Rect(io_surface_size_),
                                           scale_factor)));
 }
 
 }  // namespace content