Read compositor VSync information from platform, when possible

ash/display/display_controller.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/display/display_controller.h"
 
 #include <algorithm>
 #include <cmath>
 #include <map>
 
@@ skipping 15 matching lines @@
 #include "ui/aura/client/activation_client.h"
 #include "ui/aura/client/capture_client.h"
 #include "ui/aura/client/focus_client.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/root_window_transformer.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_property.h"
 #include "ui/aura/window_tracker.h"
 #include "ui/compositor/compositor.h"
+#include "ui/compositor/compositor_vsync_manager.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/screen.h"
 
 #if defined(OS_CHROMEOS)
 #include "base/sys_info.h"
 #include "base/time/time.h"
 #if defined(USE_X11)
 #include "ash/display/output_configurator_animation.h"
 #include "chromeos/display/output_configurator.h"
 #include "ui/base/x/x11_util.h"
@@ skipping 66 matching lines @@
   ui::SetIntProperty(xwindow, kInternalProp, kCARDINAL, internal);
   ui::SetIntProperty(xwindow, kRotationProp, kCARDINAL, xrandr_rotation);
   ui::SetIntProperty(xwindow,
                      kScaleFactorProp,
                      kCARDINAL,
                      100 * display.device_scale_factor());
 #endif
   scoped_ptr<aura::RootWindowTransformer> transformer(
       internal::CreateRootWindowTransformerForDisplay(root->window(), display));
   root->host()->SetRootWindowTransformer(transformer.Pass());
+
+  internal::DisplayMode mode;
+  if (GetDisplayManager()->GetSelectedModeForDisplayId(display.id(), &mode)) {
+    root->host()->compositor()->vsync_manager()->SetAuthoritativeVSyncInterval(
+        base::TimeDelta::FromMicroseconds(base::Time::kMicrosecondsPerSecond /
+                                          mode.refresh_rate));

[piman, 2014/02/04 04:51:01]

I think there's some cases where refresh_rate could be 0, in which case we
should skip the SetAuthoritativeVSyncInterval altogether.

[sheu, 2014/02/04 22:01:45]

And the div-by-zero.  Done.

+  }
 }
 
 }  // namespace
 
 namespace internal {
 
 // A utility class to store/restore focused/active window
 // when the display configuration has changed.
 class FocusActivationStore {
  public:
@@ skipping 603 matching lines @@
     std::string name =
         root_windows[i] == primary ? "aura_root_0" : "aura_root_x";
     gfx::AcceleratedWidget xwindow =
         root_windows[i]->GetDispatcher()->host()->GetAcceleratedWidget();
     XStoreName(gfx::GetXDisplay(), xwindow, name.c_str());
   }
 #endif
 }
 
 }  // namespace ash