Add a switch for faking channels for Variations filtering.

BUG=162417
TEST=Run Chromium (unofficial build) with --fake-variations-channel=stable and ensure that a stable experiment, such as "UMA-Dynamic-Binary-Uniformity-Trial" shows up in about:version (after restarting once).


Review URL: https://chromiumcodereview.appspot.com/11737025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@175437 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/metrics/variations/variations_service.cc

@@ -60,6 +60,31 @@ chrome::VersionInfo::Channel ConvertStudyChannelToVersionChannel(
   return chrome::VersionInfo::CHANNEL_UNKNOWN;
 }
 
+// Wrapper around channel checking, used to enable channel mocking for
+// testing. If the current browser channel is not UNKNOWN, this will return
+// that channel value. Otherwise, if the fake channel flag is provided, this
+// will return the fake channel. Failing that, this will return the UNKNOWN
+// channel.
+chrome::VersionInfo::Channel GetChannelForVariations() {
+  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
+  if (channel != chrome::VersionInfo::CHANNEL_UNKNOWN)
+    return channel;
+  std::string forced_channel =
+      CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          switches::kFakeVariationsChannel);
+  if (forced_channel == "stable")
+    channel = chrome::VersionInfo::CHANNEL_STABLE;
+  else if (forced_channel == "beta")
+    channel = chrome::VersionInfo::CHANNEL_BETA;
+  else if (forced_channel == "dev")
+    channel = chrome::VersionInfo::CHANNEL_DEV;
+  else if (forced_channel == "canary")
+    channel = chrome::VersionInfo::CHANNEL_CANARY;
+  else
+    DVLOG(1) << "Invalid channel provided: " << forced_channel;
+  return channel;
+}
+
 Study_Platform GetCurrentPlatform() {
 #if defined(OS_WIN)
   return Study_Platform_PLATFORM_WINDOWS;
@@ -136,9 +161,12 @@ bool VariationsService::CreateTrialsFromSeed(PrefService* local_prefs) {
   if (!current_version_info.is_valid())
     return false;
 
+  chrome::VersionInfo::Channel channel = GetChannelForVariations();
   for (int i = 0; i < seed.study_size(); ++i) {
-    if (ShouldAddStudy(seed.study(i), current_version_info, reference_date))
+    if (ShouldAddStudy(seed.study(i), current_version_info, reference_date,
+                       channel)) {
       CreateTrialFromStudy(seed.study(i), reference_date);
+    }
   }
 
   return true;
@@ -293,9 +321,10 @@ bool VariationsService::StoreSeedData(const std::string& seed_data,
 bool VariationsService::ShouldAddStudy(
     const Study& study,
     const chrome::VersionInfo& version_info,
-    const base::Time& reference_date) {
+    const base::Time& reference_date,
+    const chrome::VersionInfo::Channel channel) {
   if (study.has_filter()) {
-    if (!CheckStudyChannel(study.filter(), chrome::VersionInfo::GetChannel())) {
+    if (!CheckStudyChannel(study.filter(), channel)) {
       DVLOG(1) << "Filtered out study " << study.name() << " due to channel.";
       return false;
     }

chrome/browser/metrics/variations/variations_service.h

@@ -99,11 +99,13 @@ class VariationsService
                      PrefService* local_prefs);
 
   // Returns whether |study| should be disabled according to its restriction
-  // parameters. Uses |version_info| for min / max version checks and
-  // |reference_date| for the start date check.
+  // parameters. Uses |version_info| for min / max version checks,
+  // |reference_date| for the start date check and |channel| for channel
+  // checks.
   static bool ShouldAddStudy(const Study& study,
                              const chrome::VersionInfo& version_info,
-                             const base::Time& reference_date);
+                             const base::Time& reference_date,
+                             chrome::VersionInfo::Channel channel);
 
   // Checks whether a study is applicable for the given |channel| per |filter|.
   static bool CheckStudyChannel(const Study_Filter& filter,

chrome/common/chrome_switches.cc

@@ -679,6 +679,12 @@ const char kExtensionProcess[]              = "extension-process";
 // Frequency in seconds for Extensions auto-update.
 const char kExtensionsUpdateFrequency[]     = "extensions-update-frequency";
 
+// Fakes the channel of the browser for purposes of Variations filtering. This
+// is to be used for testing only. Possible values are "stable", "beta", "dev"
+// and "canary". Note that this only applies if the browser's reported channel
+// is UNKNOWN.
+const char kFakeVariationsChannel[] =       "fake-variations-channel";
+
 // These two flags are added around the switches about:flags adds to the
 // command line. This is useful to see which switches were added by about:flags
 // on about:version. They don't have any effect.

chrome/common/chrome_switches.h

@@ -189,6 +189,7 @@ extern const char kEventPageUnloadingTime[];
 extern const char kExplicitlyAllowedPorts[];
 extern const char kExtensionProcess[];
 extern const char kExtensionsUpdateFrequency[];
+extern const char kFakeVariationsChannel[];
 extern const char kFlagSwitchesBegin[];
 extern const char kFlagSwitchesEnd[];
 extern const char kFeedbackServer[];