Added GPU driver workaround for OSX multimonitor multisampling disabling

content/browser/gpu/gpu_data_manager_impl_private.cc

 // Copyright (c) 2013 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 "content/browser/gpu/gpu_data_manager_impl_private.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 223 matching lines @@
 
   GpuDataManagerImpl* manager =
       reinterpret_cast<GpuDataManagerImpl*>(gpu_data_manager);
   DCHECK(manager);
 
   uint32_t displayCount;
   CGGetActiveDisplayList(0, NULL, &displayCount);
 
   bool fireGpuSwitch = flags & kCGDisplayAddFlag;
 
-  if (displayCount != manager->GetDisplayCount()) {
+  if(manager->IsDriverBugWorkaroundActive(
+      gpu::DISABLE_MULTIMONITOR_MULTISAMPLING) &&
+      displayCount != manager->GetDisplayCount()) {

[Ken Russell (switch to Gerrit), 2013/08/29 19:28:00]

The workaround check needs to be done below in order to handle the situation
where a GPU switch event is fired for unrelated reasons. I think it would be
better to remove the check here, even though we'll be firing a GPU switch event
that has no effect.

     manager->SetDisplayCount(displayCount);
     fireGpuSwitch = true;
   }
 
   if (fireGpuSwitch)
     manager->HandleGpuSwitch();
 }
 #endif  // OS_MACOSX
 
 #if defined(OS_ANDROID)
@@ skipping 114 matching lines @@
     // Skia's software rendering is probably more efficient than going through
     // software emulation of the GPU, so use that.
     if (feature == gpu::GPU_FEATURE_TYPE_ACCELERATED_2D_CANVAS)
       return true;
     return false;
   }
 
   return (blacklisted_features_.count(feature) == 1);
 }
 
+bool GpuDataManagerImplPrivate::IsDriverBugWorkaroundActive(int feature) const {
+  return (gpu_driver_bugs_.count(feature) == 1);
+}
+
 size_t GpuDataManagerImplPrivate::GetBlacklistedFeatureCount() const {
   if (use_swiftshader_)
     return 1;
   return blacklisted_features_.size();
 }
 
 void GpuDataManagerImplPrivate::SetDisplayCount(unsigned int display_count) {
   display_count_ = display_count;
 }
 
@@ skipping 422 matching lines @@
     prefs->flash_3d_enabled = false;
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_FLASH_STAGE3D)) {
     prefs->flash_stage3d_enabled = false;
     prefs->flash_stage3d_baseline_enabled = false;
   }
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_FLASH_STAGE3D_BASELINE))
     prefs->flash_stage3d_baseline_enabled = false;
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_ACCELERATED_2D_CANVAS))
     prefs->accelerated_2d_canvas_enabled = false;
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_MULTISAMPLING)
       || display_count_ > 1)

[Ken Russell (switch to Gerrit), 2013/08/29 19:28:00]

The check on the driver bug workaround should be done here:

  if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_MULTISAMPLING) ||
      (display_count_ > 1 && manager->IsDriverBugWorkaroundActive(
          gpu::DISABLE_MULTIMONITOR_MULTISAMPLING))) {
    // ...
  }

     prefs->gl_multisampling_enabled = false;
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_3D_CSS)) {
     prefs->accelerated_compositing_for_3d_transforms_enabled = false;
     prefs->accelerated_compositing_for_animation_enabled = false;
   }
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_ACCELERATED_VIDEO))
     prefs->accelerated_compositing_for_video_enabled = false;
 
   // Accelerated video and animation are slower than regular when using
   // SwiftShader. 3D CSS may also be too slow to be worthwhile.
@@ skipping 420 matching lines @@
 
 void GpuDataManagerImplPrivate::OnGpuProcessInitFailure() {
   gpu_process_accessible_ = false;
   gpu_info_.finalized = true;
   complete_gpu_info_already_requested_ = true;
   // Some observers might be waiting.
   NotifyGpuInfoUpdate();
 }
 
 }  // namespace content