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

chrome/common/metrics/proto/system_profile.proto

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Stores information about the user's brower and system configuration.
 // The system configuration fields are recorded once per client session.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
@@ skipping 269 matching lines @@
       WIFI_PHY_LAYER_PROTOCOL_NONE = 0;
       WIFI_PHY_LAYER_PROTOCOL_ANCIENT = 1;
       WIFI_PHY_LAYER_PROTOCOL_A = 2;
       WIFI_PHY_LAYER_PROTOCOL_B = 3;
       WIFI_PHY_LAYER_PROTOCOL_G = 4;
       WIFI_PHY_LAYER_PROTOCOL_N = 5;
       WIFI_PHY_LAYER_PROTOCOL_UNKNOWN = 6;
     }
     // 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;
 
   // Information on the Google Update install that is managing this client.
   message GoogleUpdate {
     // Whether the Google Update install is system-level or user-level.
     optional bool is_system_install = 1;
 
     // The date at which Google Update last started performing an automatic
     // update check, in seconds since the Unix epoch.
@@ skipping 200 matching lines @@
   // client_id:
   //   client_key = client_id % 4096
   // Then, each installed extension is mapped into a hash bucket according to
   //   bucket = CityHash64(StringPrintf("%d:%s",
   //                                    client_key, extension_id)) % 1024
   // The client reports the set of hash buckets occupied by all installed
   // extensions.  If multiple extensions map to the same bucket, that bucket is
   // still only reported once.
   repeated int32 occupied_extension_bucket = 18;
 }