Updated OSX to blacklist multisampling when multiple monitors are connected

content/browser/gpu/gpu_data_manager_impl_private.cc

Index: content/browser/gpu/gpu_data_manager_impl_private.cc
diff --git a/content/browser/gpu/gpu_data_manager_impl_private.cc b/content/browser/gpu/gpu_data_manager_impl_private.cc
index fbc776cb9be2cf1e07915ce5184724a4a8f1e23a..74cef694525ef96d89dad54e3072667335ee7d33 100644
--- a/content/browser/gpu/gpu_data_manager_impl_private.cc
+++ b/content/browser/gpu/gpu_data_manager_impl_private.cc
@@ -216,12 +216,25 @@ std::string IntSetToString(const std::set<int>& list) {
 void DisplayReconfigCallback(CGDirectDisplayID display,
                              CGDisplayChangeSummaryFlags flags,
                              void* gpu_data_manager) {
-  if (flags & kCGDisplayAddFlag) {
-    GpuDataManagerImpl* manager =
-        reinterpret_cast<GpuDataManagerImpl*>(gpu_data_manager);
-    DCHECK(manager);
-    manager->HandleGpuSwitch();
+  if(flags == kCGDisplayBeginConfigurationFlag)
+    return; // This call contains no information about the display change
+
+  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()) {
+    manager->SetDisplayCount(displayCount);
+    fireGpuSwitch = true;
   }
+
+  if (fireGpuSwitch)
+    manager->HandleGpuSwitch();
 }
 #endif  // OS_MACOSX
 
@@ -342,6 +355,14 @@ size_t GpuDataManagerImplPrivate::GetBlacklistedFeatureCount() const {
   return blacklisted_features_.size();
 }
 
+void GpuDataManagerImplPrivate::SetDisplayCount(unsigned int display_count) {
+  display_count_ = display_count;
+}
+
+unsigned int GpuDataManagerImplPrivate::GetDisplayCount() const {
+  return display_count_;
+}
+
 gpu::GPUInfo GpuDataManagerImplPrivate::GetGPUInfo() const {
   return gpu_info_;
 }
@@ -750,7 +771,8 @@ void GpuDataManagerImplPrivate::UpdateRendererWebPrefs(
     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))
+  if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_MULTISAMPLING)
+      || display_count_ > 1)
     prefs->gl_multisampling_enabled = false;
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_3D_CSS)) {
     prefs->accelerated_compositing_for_3d_transforms_enabled = false;
@@ -899,7 +921,8 @@ GpuDataManagerImplPrivate::GpuDataManagerImplPrivate(
       update_histograms_(true),
       window_count_(0),
       domain_blocking_enabled_(true),
-      owner_(owner) {
+      owner_(owner),
+      display_count_(0) {
   DCHECK(owner_);
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kDisableAcceleratedCompositing)) {
@@ -918,6 +941,7 @@ GpuDataManagerImplPrivate::GpuDataManagerImplPrivate(
   }
 
 #if defined(OS_MACOSX)
+  CGGetActiveDisplayList (0, NULL, &display_count_);
   CGDisplayRegisterReconfigurationCallback(DisplayReconfigCallback, owner_);
 #endif  // OS_MACOSX
 }