Add a switch for faking channels for Variations filtering.

chrome/browser/metrics/variations/variations_service.cc

Index: chrome/browser/metrics/variations/variations_service.cc
diff --git a/chrome/browser/metrics/variations/variations_service.cc b/chrome/browser/metrics/variations/variations_service.cc
index b4e12da5b1bb716dbe4b3ddb0f88b9d6b3ae6461..7fdf5f46c9e62519d1f03f2f18d8b352c43da387 100644
--- a/chrome/browser/metrics/variations/variations_service.cc
+++ b/chrome/browser/metrics/variations/variations_service.cc
@@ -277,12 +277,35 @@ bool VariationsService::StoreSeedData(const std::string& seed_data,
 }
 
 // static
+chrome::VersionInfo::Channel VariationsService::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.empty()) {
+    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
+      NOTREACHED();
+  }
+  return channel;
+}
+
+// static
 bool VariationsService::ShouldAddStudy(
     const Study& study,
     const chrome::VersionInfo& version_info,
     const base::Time& reference_date) {
   if (study.has_filter()) {
-    if (!CheckStudyChannel(study.filter(), chrome::VersionInfo::GetChannel())) {
+    if (!CheckStudyChannel(study.filter(), GetChannelForVariations())) {
       DVLOG(1) << "Filtered out study " << study.name() << " due to channel.";
       return false;
     }