Use swap-promise to improve first* paint times

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index b6c7631c744cd0d7965191fd7105db39b4a6fbda..20c02ed5aee4f76ffa561abe5ca9b0b2f6455d98 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -41,6 +41,7 @@
 #include "cc/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
 #include "cc/output/latency_info_swap_promise.h"
+#include "cc/output/report_time_swap_promise.h"
 #include "cc/output/swap_promise.h"
 #include "cc/resources/single_release_callback.h"
 #include "cc/scheduler/begin_frame_source.h"
@@ -1155,4 +1156,10 @@ void RenderWidgetCompositor::SetLocalSurfaceId(
   layer_tree_host_->SetLocalSurfaceId(local_surface_id);
 }
 
+void RenderWidgetCompositor::NotifySwapTime(
+    base::Callback<void(bool, double)> callback) {
+  QueueSwapPromise(base::MakeUnique<cc::ReportTimeSwapPromise>(

[enne (OOO), 2017/05/01 21:58:11]

Agreed with sunnyps that ReportSwapTimePromise could just live in
render_widget_compositor.cc.

[panicker, 2017/05/02 00:57:04]

Done.

+      std::move(callback), base::ThreadTaskRunnerHandle::Get()));
+}
+
 }  // namespace content