[Do not submit] D3DKMTWaitForVerticalBlankEvent VSync prototype

content/browser/compositor/gpu_process_transport_factory.cc

Index: content/browser/compositor/gpu_process_transport_factory.cc
diff --git a/content/browser/compositor/gpu_process_transport_factory.cc b/content/browser/compositor/gpu_process_transport_factory.cc
index 4c0f9ee66edc593f0d353b984bf76a6e1bad82a4..31168f1dfb028e0ce710a6d749b51b951f4fb30f 100644
--- a/content/browser/compositor/gpu_process_transport_factory.cc
+++ b/content/browser/compositor/gpu_process_transport_factory.cc
@@ -11,6 +11,7 @@
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/single_thread_task_runner.h"
@@ -58,6 +59,7 @@
 #include "ui/display/types/display_snapshot.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/switches.h"
+#include "ui/gl/gl_switches.h"
 
 #if defined(USE_AURA)
 #include "content/browser/compositor/mus_browser_compositor_output_surface.h"
@@ -107,6 +109,20 @@ bool IsUsingMus() {
   return service_manager::ServiceManagerIsRemote();
 }
 
+bool IsGpuVSyncSignalSupported() {
+#if defined(OS_WIN)
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kUseD3DVSync))
+    return true;
+
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("UseD3DVSync");
+  return group_name == "Enabled";
+#else
+  return false;
+#endif  // defined(OS_WIN)
+}
+
 scoped_refptr<ui::ContextProviderCommandBuffer> CreateContextCommon(
     scoped_refptr<gpu::GpuChannelHost> gpu_channel_host,
     gpu::SurfaceHandle surface_handle,
@@ -447,20 +463,9 @@ void GpuProcessTransportFactory::EstablishedGpuChannel(
     }
   }
 
-  std::unique_ptr<cc::SyntheticBeginFrameSource> synthetic_begin_frame_source;
-  if (!compositor->GetRendererSettings().disable_display_vsync) {
-    synthetic_begin_frame_source.reset(new cc::DelayBasedBeginFrameSource(
-        base::MakeUnique<cc::DelayBasedTimeSource>(
-            compositor->task_runner().get())));
-  } else {
-    synthetic_begin_frame_source.reset(new cc::BackToBackBeginFrameSource(
-        base::MakeUnique<cc::DelayBasedTimeSource>(
-            compositor->task_runner().get())));
-  }
-  cc::BeginFrameSource* begin_frame_source = synthetic_begin_frame_source.get();
-
   BrowserCompositorOutputSurface::UpdateVSyncParametersCallback vsync_callback =
       base::Bind(&ui::Compositor::SetDisplayVSyncParameters, compositor);
+  cc::BeginFrameSource* begin_frame_source = nullptr;
 
   std::unique_ptr<BrowserCompositorOutputSurface> display_output_surface;
 #if defined(ENABLE_VULKAN)
@@ -521,6 +526,7 @@ void GpuProcessTransportFactory::EstablishedGpuChannel(
           display_output_surface =
               base::MakeUnique<GpuBrowserCompositorOutputSurface>(
                   context_provider, vsync_callback, std::move(validator));
+
         } else {
 #if defined(USE_AURA)
           std::unique_ptr<MusBrowserCompositorOutputSurface> mus_output_surface;
@@ -544,7 +550,6 @@ void GpuProcessTransportFactory::EstablishedGpuChannel(
           }
           // We use the ExternalBeginFrameSource provided by the output surface
           // instead of our own synthetic one.
-          synthetic_begin_frame_source.reset();
           begin_frame_source = mus_output_surface->GetBeginFrameSource();
           DCHECK(begin_frame_source);
           display_output_surface = std::move(mus_output_surface);
@@ -556,7 +561,29 @@ void GpuProcessTransportFactory::EstablishedGpuChannel(
     }
   }
 
-  data->display_output_surface = display_output_surface.get();
+  std::unique_ptr<cc::SyntheticBeginFrameSource> synthetic_begin_frame_source;
+
+  if (!begin_frame_source) {
+    if (!compositor->GetRendererSettings().disable_display_vsync) {
+      GpuVSyncControl* vsync_control =
+          display_output_surface->GetVSyncControl();
+      if (vsync_control && IsGpuVSyncSignalSupported()) {
+        synthetic_begin_frame_source.reset(
+            new GpuVSyncBeginFrameSource(vsync_control));
+      } else {
+        synthetic_begin_frame_source.reset(new cc::DelayBasedBeginFrameSource(
+            base::MakeUnique<cc::DelayBasedTimeSource>(
+                compositor->task_runner().get())));
+      }
+    } else {
+      synthetic_begin_frame_source.reset(new cc::BackToBackBeginFrameSource(
+          base::MakeUnique<cc::DelayBasedTimeSource>(
+              compositor->task_runner().get())));
+    }
+
+    begin_frame_source = synthetic_begin_frame_source.get();
+  }
+
   if (data->reflector)
     data->reflector->OnSourceSurfaceReady(data->display_output_surface);