metricsd: Fix the update channel parsing logic.

libupdate_engine_client returns the channel as "stable-channel",
"dev-channel" or "beta-channel". This CL updates the parsing logic to
match this format.

Bug: 25669566
Test: unit tests
Test: manual: The reported channel matches what update_engine_client
  --show_channel reports.

Change-Id: Ic6e52df892ae0b438f58fc05b178d5844d6674d0
diff --git a/uploader/system_profile_cache.cc b/uploader/system_profile_cache.cc
index f7060a2..637cf9e 100644
--- a/uploader/system_profile_cache.cc
+++ b/uploader/system_profile_cache.cc
@@ -179,13 +179,13 @@
 
 metrics::SystemProfileProto_Channel SystemProfileCache::ProtoChannelFromString(
     const std::string& channel) {
-  if (channel == "stable") {
+  if (channel == "stable-channel") {
     return metrics::SystemProfileProto::CHANNEL_STABLE;
-  } else if (channel == "dev") {
+  } else if (channel == "dev-channel") {
     return metrics::SystemProfileProto::CHANNEL_DEV;
-  } else if (channel == "beta") {
+  } else if (channel == "beta-channel") {
     return metrics::SystemProfileProto::CHANNEL_BETA;
-  } else if (channel == "canary") {
+  } else if (channel == "canary-channel") {
     return metrics::SystemProfileProto::CHANNEL_CANARY;
   }
 
diff --git a/uploader/upload_service_test.cc b/uploader/upload_service_test.cc
index 236376a..47e7b91 100644
--- a/uploader/upload_service_test.cc
+++ b/uploader/upload_service_test.cc
@@ -214,10 +214,10 @@
       metrics::SystemProfileProto::CHANNEL_UNKNOWN);
 
   EXPECT_EQ(metrics::SystemProfileProto::CHANNEL_DEV,
-            SystemProfileCache::ProtoChannelFromString("dev"));
+            SystemProfileCache::ProtoChannelFromString("dev-channel"));
 
   EXPECT_EQ(metrics::SystemProfileProto::CHANNEL_STABLE,
-            SystemProfileCache::ProtoChannelFromString("stable"));
+            SystemProfileCache::ProtoChannelFromString("stable-channel"));
 
   EXPECT_EQ(metrics::SystemProfileProto::CHANNEL_UNKNOWN,
             SystemProfileCache::ProtoChannelFromString("this is a test"));