Only set the channel from ExtensionSystem if there hasn't been one set already.

chrome/common/extensions/features/feature.cc

Index: chrome/common/extensions/features/feature.cc
diff --git a/chrome/common/extensions/features/feature.cc b/chrome/common/extensions/features/feature.cc
index 3da8726e386acf3003ece3a22741e6612cb42836..6c6409caa557041c44b915fc34791e8ea0cf9a4a 100644
--- a/chrome/common/extensions/features/feature.cc
+++ b/chrome/common/extensions/features/feature.cc
@@ -62,7 +62,8 @@ std::string GetChannelName(VersionInfo::Channel channel) {
   return "unknown";
 }
 
-VersionInfo::Channel g_current_channel = VersionInfo::CHANNEL_STABLE;
+const VersionInfo::Channel kDefaultChannel = VersionInfo::CHANNEL_STABLE;
+VersionInfo::Channel g_current_channel = kDefaultChannel;
 
 // TODO(aa): Can we replace all this manual parsing with JSON schema stuff?
 
@@ -334,4 +335,9 @@ void Feature::SetCurrentChannel(VersionInfo::Channel channel) {
   g_current_channel = channel;
 }
 
+// static
+chrome::VersionInfo::Channel Feature::GetDefaultChannel() {
+  return kDefaultChannel;
+}
+
 }  // namespace