Implement blacklist's force GPU capability in dual GPU machines.

content/browser/gpu/gpu_data_manager_impl.cc

Index: content/browser/gpu/gpu_data_manager_impl.cc
===================================================================
--- content/browser/gpu/gpu_data_manager_impl.cc	(revision 156326)
+++ content/browser/gpu/gpu_data_manager_impl.cc	(working copy)
@@ -48,7 +48,7 @@
     : complete_gpu_info_already_requested_(false),
       gpu_feature_type_(content::GPU_FEATURE_TYPE_UNKNOWN),
       preliminary_gpu_feature_type_(content::GPU_FEATURE_TYPE_UNKNOWN),
-      gpu_switching_(content::GPU_SWITCHING_AUTOMATIC),
+      gpu_switching_(content::GPU_SWITCHING_OPTION_AUTOMATIC),
       observer_list_(new GpuDataManagerObserverList),
       software_rendering_(false),
       card_blacklisted_(false),
@@ -60,6 +60,14 @@
   }
   if (command_line->HasSwitch(switches::kDisableGpu))
     BlacklistCard();
+  if (command_line->HasSwitch(switches::kGpuSwitching)) {
+    std::string option_string = command_line->GetSwitchValueASCII(
+        switches::kGpuSwitching);
+    GpuSwitchingOption option = gpu_util::StringToGpuSwitchingOption(
+        option_string);
+    if (option != content::GPU_SWITCHING_OPTION_UNKNOWN)
+      gpu_switching_ = option;
+  }
 }
 
 void GpuDataManagerImpl::Initialize(
@@ -137,7 +145,8 @@
                             decision.blacklisted_features);
     }
     UpdateBlacklistedFeatures(decision.blacklisted_features);
-    gpu_switching_ = decision.gpu_switching;
+    if (decision.gpu_switching != content::GPU_SWITCHING_OPTION_UNKNOWN)
+      gpu_switching_ = decision.gpu_switching;
   }
 
   {
@@ -299,6 +308,18 @@
   } else if (!use_gl.empty()) {
     command_line->AppendSwitchASCII(switches::kUseGL, use_gl);
   }
+  switch (gpu_switching_) {
+    case content::GPU_SWITCHING_OPTION_FORCE_DISCRETE:
+      command_line->AppendSwitchASCII(switches::kGpuSwitching,
+          switches::kGpuSwitchingOptionNameForceDiscrete);
+      break;
+    case content::GPU_SWITCHING_OPTION_FORCE_INTEGRATED:
+      command_line->AppendSwitchASCII(switches::kGpuSwitching,
+          switches::kGpuSwitchingOptionNameForceIntegrated);
+      break;
+    default:
+      break;
+  }
 
   if (!swiftshader_path.empty())
     command_line->AppendSwitchPath(switches::kSwiftShaderPath,