Record Mobile Operator ID in UMA report. This is Android only for now.

chrome/common/metrics/proto/system_profile.proto

Index: chrome/common/metrics/proto/system_profile.proto
diff --git a/chrome/common/metrics/proto/system_profile.proto b/chrome/common/metrics/proto/system_profile.proto
index fd339ec5d26db48c249c9d30b0d7827b1cc0f50a..0a3b7e9ae6b395c267ff5bf6c727c1bcfffd0342 100644
--- a/chrome/common/metrics/proto/system_profile.proto
+++ b/chrome/common/metrics/proto/system_profile.proto
@@ -287,6 +287,14 @@ message SystemProfileProto {
     }
     // The physical layer mode of the associated wifi access point, if any.
     optional WifiPHYLayerProtocol wifi_phy_layer_protocol = 4;
+
+    // Network Operator Information.
+    message NetworkOperator {
+      // MCC+MNC (mobile country code + mobile network code) of the
+      // the current registered operator.

[Alexei Svitkine (slow), 2014/04/23 16:54:11]

What is the "current registered operator"?

Can this change while Chrome is running? If so, what will be logged? (This
should be documented.)

Is there a reason this is a separate message rather than using the id below?

[bolian, 2014/04/23 17:29:39]

I removed the message type since there is only one field for now. I was thinking
more fields (like operator name) might be needed. But we can do that later.

Yes, the value can change - there is no mobile network at the spot.
Updated comment.

+      optional string id = 1;

[Alexei Svitkine (slow), 2014/04/23 16:54:11]

Should this field be called mmc_mnc? I think that's the terminology used in
other products' logs.

[bolian, 2014/04/23 17:29:39]

Done. Changed id to mcc_mnc (you mean mcc_mnc, right?).  MCC and MNC are the
terms used the Android SDK API that provides this data.

+    }
+    optional NetworkOperator network_operator = 5;
   }
   optional Network network = 13;