Enable by default threaded compositing on windows and FCM on mac

chrome/browser/chrome_gpu_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 "chrome/browser/chrome_gpu_util.h"
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/version.h"
@@ skipping 56 matching lines @@
   // field trial.
   if (!ShouldRunCompositingFieldTrial()) {
     DisableCompositingFieldTrial();
     return;
   }
 
   const base::FieldTrial::Probability kDivisor = 3;
   scoped_refptr<base::FieldTrial> trial(
     base::FieldTrialList::FactoryGetFieldTrial(
         content::kGpuCompositingFieldTrialName, kDivisor,
-        "disable", 2012, 12, 31, NULL));
+        "disable", 2017, 12, 31, NULL));
 
   // Produce the same result on every run of this client.
   trial->UseOneTimeRandomization();
 
   base::FieldTrial::Probability force_compositing_mode_probability = 0;
   base::FieldTrial::Probability threaded_compositing_probability = 0;
 
+  // Threaded compositing mode isn't feature complete on mac or linux yet:
+  // http://crbug.com/133602 for mac
+  // http://crbug.com/140866 for linux
+
+#if defined(OS_WIN)
+  // threaded-compositing turned on by default on Windows.
+  // (Windows XP is excluded explicitly in ShouldRunCompositingFieldTrial)
+  threaded_compositing_probability = 3;
+#elif defined(OS_MACOSX)
+  // force-compositing-mode turned on by default on mac.
+  force_compositing_mode_probability = 3;
+#elif defined(OS_LINUX)
+  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
+  if (channel != chrome::VersionInfo::CHANNEL_STABLE &&
+      channel != chrome::VersionInfo::CHANNEL_BETA) {
+    // On channels < beta, force-compositing-mode and
+    // threaded-compositing on with 1/3 probability each.

[Nico, 2012/09/13 01:37:21]

This is gonna be hell for bug triage. What are the plans to mitigate this?

+    force_compositing_mode_probability = 1;
+    threaded_compositing_mode_probability = 1;
+  }
+#endif
+
   chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
   if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
       channel == chrome::VersionInfo::CHANNEL_BETA) {
     // Stable and Beta channels: Non-threaded force-compositing-mode on by
     // default (mac and windows only).
 #if defined(OS_WIN) || defined(OS_MACOSX)
     force_compositing_mode_probability = 3;
 #endif
   } else if (channel == chrome::VersionInfo::CHANNEL_DEV ||
              channel == chrome::VersionInfo::CHANNEL_CANARY) {
@@ skipping 44 matching lines @@
         ResourceBundle::GetSharedInstance().GetRawDataResource(
             IDR_GPU_BLACKLIST, ui::SCALE_FACTOR_NONE));
     gpu_blacklist_json_string = gpu_blacklist_json.as_string();
   }
   content::GpuDataManager::GetInstance()->Initialize(
       chrome_version_string, gpu_blacklist_json_string);
 }
 
 }  // namespace gpu_util;