Revert of Remove EnableThreadedCompositing from the browser.

content/browser/gpu/compositor_util.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 "content/browser/gpu/compositor_util.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "build/build_config.h"
@@ skipping 150 matching lines @@
   if (command_line.HasSwitch(cc::switches::kEnablePinchVirtualViewport))
     return true;
 
 #if defined(OS_CHROMEOS)
   return true;
 #else
   return false;
 #endif
 }
 
+bool IsThreadedCompositingEnabled() {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  // Command line switches take precedence over blacklist.
+  if (command_line.HasSwitch(switches::kDisableThreadedCompositing))
+    return false;
+  if (command_line.HasSwitch(switches::kEnableThreadedCompositing))
+    return true;
+
+#if defined(USE_AURA) || defined(OS_MACOSX)
+  // We always want threaded compositing on Aura and Mac (the fallback is a
+  // threaded software compositor).
+  return true;
+#else
+  return false;
+#endif
+}
+
 bool IsDelegatedRendererEnabled() {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   bool enabled = false;
 
 #if defined(USE_AURA)
   // Enable on Aura.
   enabled = true;
 #endif
 
   // Flags override.
   enabled |= command_line.HasSwitch(switches::kEnableDelegatedRenderer);
   enabled &= !command_line.HasSwitch(switches::kDisableDelegatedRenderer);
 
   // Needs compositing, and thread.
+  if (enabled && !IsThreadedCompositingEnabled()) {
+    enabled = false;
+    LOG(ERROR) << "Disabling delegated-rendering because it needs "
+               << "force-compositing-mode and threaded-compositing.";
+  }
+
   return enabled;
 }
 
 bool IsImplSidePaintingEnabled() {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   if (command_line.HasSwitch(switches::kDisableImplSidePainting))
     return false;
   else if (command_line.HasSwitch(switches::kEnableImplSidePainting))
     return true;
   else if (command_line.HasSwitch(
       switches::kEnableBleedingEdgeRenderingFastPaths))
     return true;
 
 #if defined(OS_MACOSX) || defined(OS_WIN)
   return false;
 #else
-  return true;
+  return IsThreadedCompositingEnabled();
 #endif
 }
 
 bool IsGpuRasterizationEnabled() {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   if (!IsImplSidePaintingEnabled())
     return false;
 
   if (command_line.HasSwitch(switches::kDisableGpuRasterization))
@@ skipping 54 matching lines @@
     } else {
       status = "enabled";
       if (gpu_feature_info.name == kWebGLFeatureName &&
           manager->IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_GPU_COMPOSITING))
         status += "_readback";
       if (gpu_feature_info.name == kRasterizationFeatureName) {
         if (IsForceGpuRasterizationEnabled())
           status += "_force";
       }
     }
+    if (gpu_feature_info.name == kGpuCompositingFeatureName) {
+      if (IsThreadedCompositingEnabled())
+        status += "_threaded";
+    }
     feature_status_dict->SetString(
         gpu_feature_info.name.c_str(), status.c_str());
   }
   return feature_status_dict;
 }
 
 base::Value* GetProblems() {
   GpuDataManagerImpl* manager = GpuDataManagerImpl::GetInstance();
   std::string gpu_access_blocked_reason;
   bool gpu_access_blocked =
@@ skipping 34 matching lines @@
   return problem_list;
 }
 
 base::Value* GetDriverBugWorkarounds() {
   base::ListValue* workaround_list = new base::ListValue();
   GpuDataManagerImpl::GetInstance()->GetDriverBugWorkarounds(workaround_list);
   return workaround_list;
 }
 
 }  // namespace content