Always enable FCM on Windows.

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/public/browser/compositor_util.h"
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
+#include "build/build_config.h"
 #include "content/public/browser/gpu_data_manager.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/common/content_switches.h"
 #include "gpu/config/gpu_feature_type.h"
 
 namespace content {
 
 namespace {
 
 bool CanDoAcceleratedCompositing() {
@@ skipping 10 matching lines @@
   if (manager->ShouldUseSwiftShader())
     return false;
 
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kDisableAcceleratedCompositing))
     return false;
 
   return true;
 }
 
-bool IsForceCompositingModeBlacklisted() {
-  return GpuDataManager::GetInstance()->IsFeatureBlacklisted(

[gab, 2013/08/15 20:07:49]

This is already checked by CanDoAcceleratedCompositing().

-      gpu::GPU_FEATURE_TYPE_FORCE_COMPOSITING_MODE);
-}
-
 }  // namespace
 
 bool IsThreadedCompositingEnabled() {
 #if defined(OS_WIN) && defined(USE_AURA)
   // We always want compositing on Aura Windows.
   return true;
 #endif
 
-  if (!CanDoAcceleratedCompositing())
-    return false;
-
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   // Command line switches take precedence over blacklist and field trials.

[gab, 2013/08/15 20:07:49]

Group command-line switches check together and moved
CanDoAcceleratedCompositing() check below to respect this comment.

   if (command_line.HasSwitch(switches::kDisableForceCompositingMode) ||
-      command_line.HasSwitch(switches::kDisableThreadedCompositing))
+      command_line.HasSwitch(switches::kDisableThreadedCompositing)) {
     return false;
+  } else if (command_line.HasSwitch(switches::kEnableThreadedCompositing)) {
+    return true;
+  }
 
 #if defined(OS_CHROMEOS)
   // We always want threaded compositing on  ChromeOS unless it's explicitly
   // disabled above.
   return true;
 #endif
 
-  if (command_line.HasSwitch(switches::kEnableThreadedCompositing))
-    return true;
-
-  if (IsForceCompositingModeBlacklisted())
+  if (!CanDoAcceleratedCompositing())
     return false;
 
   base::FieldTrial* trial =
       base::FieldTrialList::Find(kGpuCompositingFieldTrialName);
   return trial &&
          trial->group_name() == kGpuCompositingFieldTrialThreadEnabledName;
 }
 
 bool IsForceCompositingModeEnabled() {
 #if defined(OS_WIN) && defined(USE_AURA)
   // We always want compositing on Aura Windows.
   return true;
 #endif
 
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  // Command line switches take precedence over blacklisting and field trials.
+  if (command_line.HasSwitch(switches::kDisableForceCompositingMode))
+    return false;
+  else if (command_line.HasSwitch(switches::kForceCompositingMode))
+    return true;
+
+#if defined(OS_CHROMEOS)
+  // We always want compositing ChromeOS unless it's explicitly disabled above.
+  return true;
+#endif

[Zhenyao Mo, 2013/08/15 20:23:37]

This should be below the CanDOAcceleratedCompositing(), because if it's
blacklisted, you don't want to turn it on.

[gab, 2013/08/15 21:03:19]

Done.

+
   if (!CanDoAcceleratedCompositing())
     return false;
 
-  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
-
-  // Command line switches take precedence over blacklisting and field trials.
-  if (command_line.HasSwitch(switches::kDisableForceCompositingMode))
-    return false;
-
-#if defined(OS_CHROMEOS)
-  // We always want compositing ChromeOS unless it's explicitly disabled above.
+#if defined(OS_WIN)
+  // Windows Vista+ has been shipping with FCM enabled at 100% since M24; skip
+  // the field trial check to ensure this is always enabled on the try bots.
+  // TODO(gab): Do the same thing in IsThreadedCompositingEnabled() once this is
+  // stable.
+  // TODO(gab): Do the same thing for Mac OS (which has been enabled at 100%
+  // since M28) as well and get rid of the field trial code.
   return true;
-#endif
-
-  if (command_line.HasSwitch(switches::kForceCompositingMode))
-    return true;
-
-  if (IsForceCompositingModeBlacklisted())
-    return false;
-
+#else

[Zhenyao Mo, 2013/08/15 20:23:37]

According to code style, this #else is unnecessary and should not be here.

[gab, 2013/08/15 21:03:19]

Done.

   base::FieldTrial* trial =
       base::FieldTrialList::Find(kGpuCompositingFieldTrialName);
 
   // Force compositing is enabled in both the force compositing
   // and threaded compositing mode field trials.
   return trial &&
         (trial->group_name() ==
             kGpuCompositingFieldTrialForceCompositingEnabledName ||
          trial->group_name() == kGpuCompositingFieldTrialThreadEnabledName);
+#endif
 }
 
 }  // namespace content