gpu: Add disable_arb_sync workaround and blacklist some MacOSX drivers.

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index cfbee736f65eadea561c9c61bd60aca1c6501744..082c2214b1bdff438ffe381f45b422a292ca535e 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -802,8 +802,13 @@ void FeatureInfo::InitializeFeatures() {
   }
   egl_khr_fence_sync = gfx::g_driver_egl.ext.b_EGL_KHR_fence_sync;
 #endif
+  bool arb_sync = false;
+  if (workarounds_.disable_arb_sync) {
+    gfx::g_driver_gl.ext.b_GL_ARB_sync = false;
+  }
+  arb_sync = gfx::g_driver_gl.ext.b_GL_ARB_sync;

[no sievers, 2014/05/30 18:05:20]

ultra-nit: I guess you could remove line 805 and declare arb_sync here (same
above for egl_khr_fence_sync).

[reveman, 2014/05/30 19:16:17]

Cleaned this up a bit in latest patch by not using arb_sync variable at all. The
egl_khr_fence_sync variable and declaring it before the workaround check is
necessary because of the !OS_MACOSX ifdef.

   bool ui_gl_fence_works = is_es3 || extensions.Contains("GL_NV_fence") ||
-                           extensions.Contains("GL_ARB_sync") ||
+                           arb_sync ||
                            egl_khr_fence_sync;
   UMA_HISTOGRAM_BOOLEAN("GPU.FenceSupport", ui_gl_fence_works);