Make disable vsync run the renderer independently

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index a08204f612aeabd79e75fb50544840835788f396..35ea9dc39daaa9f6bbafdce679736a879f35a46b 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -108,16 +108,10 @@ Compositor::Compositor(ui::ContextFactory* context_factory,
                                                  : kDefaultRefreshRate;
   settings.main_frame_before_activation_enabled = false;
   if (command_line->HasSwitch(switches::kDisableGpuVsync)) {
-    std::string display_vsync_string =
-        command_line->GetSwitchValueASCII(switches::kDisableGpuVsync);
-    if (display_vsync_string == "gpu") {
-      settings.renderer_settings.disable_display_vsync = true;
-    } else if (display_vsync_string == "beginframe") {
-      settings.wait_for_beginframe_interval = false;
-    } else {
-      settings.renderer_settings.disable_display_vsync = true;
-      settings.wait_for_beginframe_interval = false;
-    }
+    // The browser compositor is always driven directly by the display
+    // compositor, so there is no difference between different versions
+    // of disable vsync like there is in the renderer in a pre-mus world.
+    settings.renderer_settings.disable_display_vsync = true;
   }
   settings.renderer_settings.partial_swap_enabled =
       !command_line->HasSwitch(switches::kUIDisablePartialSwap);