Add GpuVsync feature

Add a feature to control if GpuVsync is enabled or not, in addition to
the --disable-gpu-vsync flag. The feature is on by default so this
should be a no-op change. This is intended to be used in a finch trial
to see what the impact of disabling GPU vsync is after the feature
freeze is over.

Bug: 43611
Change-Id: I09715832b48e5ba9fe11e04404ed68fb441a5dfa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2597637Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Commit-Queue: kylechar <kylechar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#838656}

gpu/ipc/service/pass_through_image_transport_surface.cc

@@ -8,14 +8,13 @@
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
-#include "base/command_line.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/histogram_macros_local.h"
 #include "build/build_config.h"
 #include "gpu/command_buffer/common/swap_buffers_complete_params.h"
 #include "ui/gfx/vsync_provider.h"
 #include "ui/gl/gl_context.h"
-#include "ui/gl/gl_switches.h"
+#include "ui/gl/gl_features.h"
 
 namespace gpu {
 
@@ -28,10 +27,6 @@ int g_current_swap_generation_ = 0;
 int g_num_swaps_in_current_swap_generation_ = 0;
 int g_last_multi_window_swap_generation_ = 0;
 
-bool HasSwitch(const char switch_constant[]) {
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(switch_constant);
-}
-
 }  // anonymous namespace
 
 PassThroughImageTransportSurface::PassThroughImageTransportSurface(
@@ -39,13 +34,12 @@ PassThroughImageTransportSurface::PassThroughImageTransportSurface(
     gl::GLSurface* surface,
     bool override_vsync_for_multi_window_swap)
     : GLSurfaceAdapter(surface),
-      is_gpu_vsync_disabled_(HasSwitch(switches::kDisableGpuVsync)),
+      is_gpu_vsync_disabled_(!features::UseGpuVsync()),
       is_multi_window_swap_vsync_override_enabled_(
           override_vsync_for_multi_window_swap),
       delegate_(delegate) {}
 
-PassThroughImageTransportSurface::~PassThroughImageTransportSurface() {
-}
+PassThroughImageTransportSurface::~PassThroughImageTransportSurface() = default;
 
 bool PassThroughImageTransportSurface::Initialize(gl::GLSurfaceFormat format) {
   // The surface is assumed to have already been initialized.

ui/gl/direct_composition_surface_win.cc

@@ -20,6 +20,7 @@
 #include "ui/gl/dc_layer_tree.h"
 #include "ui/gl/direct_composition_child_surface_win.h"
 #include "ui/gl/gl_angle_util_win.h"
+#include "ui/gl/gl_features.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_switches.h"
 #include "ui/gl/gpu_switching_manager.h"
@@ -652,8 +653,7 @@ bool DirectCompositionSurfaceWin::IsSwapChainTearingSupported() {
 // static
 bool DirectCompositionSurfaceWin::AllowTearing() {
   // Swap chain tearing is used only if vsync is disabled explicitly.
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(
-             switches::kDisableGpuVsync) &&
+  return features::UseGpuVsync() &&
          DirectCompositionSurfaceWin::IsSwapChainTearingSupported();
 }
 

ui/gl/gl_features.cc

@@ -4,9 +4,17 @@
 
 #include "ui/gl/gl_features.h"
 
+#include "base/command_line.h"
+#include "base/feature_list.h"
 #include "build/chromeos_buildflags.h"
+#include "ui/gl/gl_switches.h"
 
 namespace features {
+namespace {
+
+const base::Feature kGpuVsync{"GpuVsync", base::FEATURE_ENABLED_BY_DEFAULT};
+
+}  // namespace
 
 // Use the passthrough command decoder by default.  This can be overridden with
 // the --use-cmd-decoder=passthrough or --use-cmd-decoder=validating flags.
@@ -24,4 +32,10 @@ const base::Feature kDefaultPassthroughCommandDecoder{
 #endif
 };
 
+bool UseGpuVsync() {
+  return !base::CommandLine::ForCurrentProcess()->HasSwitch(
+             switches::kDisableGpuVsync) &&
+         base::FeatureList::IsEnabled(kGpuVsync);
+}
+
 }  // namespace features

ui/gl/gl_features.h

@@ -11,6 +11,9 @@
 
 namespace features {
 
+// Controls if GPU should synchronize presentation with vsync.
+GL_EXPORT bool UseGpuVsync();
+
 // All features in alphabetical order. The features should be documented
 // alongside the definition of their values in the .cc file.
 GL_EXPORT extern const base::Feature kDefaultPassthroughCommandDecoder;