Adding a field trial for testing --force-compositing-mode on 50% of

chrome/browser/chrome_browser_main.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_browser_main.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 142 matching lines @@
 #include "chrome/installer/util/install_util.h"
 #include "chrome/installer/util/shell_util.h"
 #include "net/base/net_util.h"
 #include "printing/printed_document.h"
 #include "ui/base/l10n/l10n_util_win.h"
 #endif  // defined(OS_WIN)
 
 #if defined(OS_MACOSX)
 #include <Security/Security.h>
 
+#include "base/mac/mac_util.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "chrome/browser/mac/keystone_glue.h"
 #endif
 
 #if defined(ENABLE_RLZ)
 #include "chrome/browser/rlz/rlz.h"
 #endif
 
 #if defined(TOOLKIT_VIEWS)
 #include "ui/views/focus/accelerator_handler.h"
@@ skipping 334 matching lines @@
 }  // namespace
 
 namespace chrome_browser {
 // This error message is not localized because we failed to load the
 // localization data files.
 const char kMissingLocaleDataTitle[] = "Missing File Error";
 const char kMissingLocaleDataMessage[] =
     "Unable to find locale data files. Please reinstall.";
 }  // namespace chrome_browser
 
+namespace chrome_browser_trials {
+bool g_in_force_compositing_mode_trial = false;

[jar (doing other things), 2012/06/07 16:10:44]

Rather than using a global, which then puts a need to include the header for
this file....  The field_trial.h defines the generic test function:
base::FieldTrialList::Find(...)
Which can be used to answer the question from anywhere (never a problem with
#include dependency issues).

*IF* you really find you need to often ask the question, you can certainly cache
the result locally, assuming you understand the initialization order.  In this
case, you're correctly calling for this to be set up before we even go
multi-threaded, so you are assured this will be done in advance of most any
uses.

+}  // namespace chrome_browser_trials
+
 // BrowserMainParts ------------------------------------------------------------
 
 // static
 bool ChromeBrowserMainParts::disable_enforcing_cookie_policies_for_tests_ =
     false;
 
 ChromeBrowserMainParts::ChromeBrowserMainParts(
     const content::MainFunctionParams& parameters)
     : parameters_(parameters),
       parsed_command_line_(parameters.command_line),
@@ skipping 477 matching lines @@
   // Create a 100% field trial based on the brand code.
   if (auto_launch_trial::IsInExperimentGroup(brand)) {
     base::FieldTrialList::CreateFieldTrial(kAutoLaunchTrialName,
                                            kAutoLaunchTrialAutoLaunchGroup);
   } else if (auto_launch_trial::IsInControlGroup(brand)) {
     base::FieldTrialList::CreateFieldTrial(kAutoLaunchTrialName,
                                            kAutoLaunchTrialControlGroup);
   }
 }
 
+void ChromeBrowserMainParts::ForceCompositingModeFieldTrial() {
+// Enable the field trial only on desktop OS's.
+#if !(defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX))
+  return;
+#endif
+  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
+  // Only run the trial on the Canary channel.
+  if (channel != chrome::VersionInfo::CHANNEL_CANARY)
+    return;
+#if defined(OS_WIN)
+  // Don't run the trial on Windows XP.
+  if (base::win::GetVersion() < base::win::VERSION_VISTA)
+    return;
+#elif defined(OS_MACOSX)
+  // Accelerated compositing is only implemented on Mac OSX 10.6 or later.
+  if (base::mac::IsOSLeopardOrEarlier())
+    return;
+#endif
+
+  const base::FieldTrial::Probability kDivisor = 100;
+  scoped_refptr<base::FieldTrial> trial(
+    base::FieldTrialList::FactoryGetFieldTrial(
+        "ForceCompositingMode", kDivisor, "disable", 2012, 12, 31, NULL));
+
+  // Produce the same result on every run of this client.
+  trial->UseOneTimeRandomization();
+  // 50% probability of being in the enabled group.
+  const base::FieldTrial::Probability kEnableProbability = 50;
+  int enable_group = trial->AppendGroup("enable", kEnableProbability);
+
+  chrome_browser_trials::g_in_force_compositing_mode_trial =
+      (trial->group() == enable_group);
+  UMA_HISTOGRAM_BOOLEAN("GPU.InForceCompositingModeFieldTrial",
+      chrome_browser_trials::g_in_force_compositing_mode_trial);
+}
+
 void ChromeBrowserMainParts::DomainBoundCertsFieldTrial() {
   chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
   if (channel == chrome::VersionInfo::CHANNEL_CANARY) {
     net::SSLConfigService::EnableDomainBoundCertsTrial();
   } else if (channel == chrome::VersionInfo::CHANNEL_DEV &&
              base::FieldTrialList::IsOneTimeRandomizationEnabled()) {
     const base::FieldTrial::Probability kDivisor = 100;
     // 10% probability of being in the enabled group.
     const base::FieldTrial::Probability kEnableProbability = 10;
     scoped_refptr<base::FieldTrial> trial =
@@ skipping 71 matching lines @@
   if (!proxy_policy_is_set)
     ProxyConnectionsFieldTrial();
   prerender::ConfigurePrefetchAndPrerender(parsed_command_line());
   SpdyFieldTrial();
   ConnectBackupJobsFieldTrial();
   WarmConnectionFieldTrial();
   PredictorFieldTrial();
   DefaultAppsFieldTrial();
   AutoLaunchChromeFieldTrial();
   DomainBoundCertsFieldTrial();
+  ForceCompositingModeFieldTrial();

[jar (doing other things), 2012/06/07 16:10:44]

nit: I think you should call this a "CompositingMode" field trial.  When I read
the function name, it looks like "Force" the use of the "CompositingMode" field
trial.

   SetupUniformityFieldTrials();
   AutocompleteFieldTrial::Activate();
 }
 
 void ChromeBrowserMainParts::StartMetricsRecording() {
   MetricsService* metrics = g_browser_process->metrics_service();
   if (parsed_command_line_.HasSwitch(switches::kMetricsRecordingOnly) ||
       parsed_command_line_.HasSwitch(switches::kEnableBenchmarking)) {
     // If we're testing then we don't care what the user preference is, we turn
     // on recording, but not reporting, otherwise tests fail.
@@ skipping 890 matching lines @@
     if (base::win::GetVersion() <= base::win::VERSION_XP)
       uma_name += "_XP";
 
     uma_name += "_PreRead_";
     uma_name += pre_read_percentage;
     AddPreReadHistogramTime(uma_name.c_str(), time);
   }
 #endif
 #endif
 }