Add a gpu.SwapBuffers synthetic delay to PostSubBuffer.

base/debug/trace_event_impl.h

Index: base/debug/trace_event_impl.h
diff --git a/base/debug/trace_event_impl.h b/base/debug/trace_event_impl.h
index 5e22c0e04eb4465e45fac192471cbe01ab34b7db..e5a6dbd71f9b09ed6a7c3f82da41ffe0df80f703 100644
--- a/base/debug/trace_event_impl.h
+++ b/base/debug/trace_event_impl.h
@@ -299,13 +299,14 @@ class BASE_EXPORT CategoryFilter {
   //
   // Category filters can also be used to configure synthetic delays.
   //
-  // Example: CategoryFilter("DELAY(gpu.SwapBuffers;16)"); would make swap
+  // Example: CategoryFilter("DELAY(gpu.PresentingFrame;16)"); would make swap
   //          buffers always take at least 16 ms.
-  // Example: CategoryFilter("DELAY(gpu.SwapBuffers;16;oneshot)"); would
-  //          make swap buffers take at least 16 ms the first time it is called.
-  // Example: CategoryFilter("DELAY(gpu.SwapBuffers;16;alternating)"); would
-  //          make swap buffers take at least 16 ms every other time it is
+  // Example: CategoryFilter("DELAY(gpu.PresentingFrame;16;oneshot)"); would
+  //          make swap buffers take at least 16 ms the first time it is
   //          called.
+  // Example: CategoryFilter("DELAY(gpu.PresentingFrame;16;alternating)");
+  //          would make swap buffers take at least 16 ms every other time it
+  //          is called.
   explicit CategoryFilter(const std::string& filter_string);
 
   CategoryFilter(const CategoryFilter& cf);