Change cast's UMA product type from CHROME to CAST.

components/metrics/proto/chrome_user_metrics_extension.proto

 // Copyright 2014 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.
 //
 // Protocol buffer for Chrome UMA (User Metrics Analysis).
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 option java_outer_classname = "ChromeUserMetricsExtensionProtos";
@@ skipping 13 matching lines @@
 
 // Next tag: 13
 message ChromeUserMetricsExtension {
   // The product (i.e. end user application) for a given UMA log.
   enum Product {
     // Google Chrome product family.
     CHROME = 0;
 
     // UMA metrics from Android Webview.
     ANDROID_WEBVIEW = 20;
+
+    // Cast receivers, e.g. Chromecast
+    CAST = 35;
   }
   // The product corresponding to this log. The field type is int32 instead of
   // Product so that downstream users of the Chromium metrics component can
   // introduce products without needing to make changes to the Chromium code
   // (though they still need to add the new product to the server-side enum).
   // Note: The default value is Chrome, so Chrome products will not transmit
   // this field.
   optional int32 product = 10 [default = 0];
 
   // The id of the client install that generated these events.
@@ skipping 27 matching lines @@
 
   // A list of all collected sample-based profiles since the last UMA upload.
   repeated SampledProfile sampled_profile = 11;
 
   // Additional data related with Cast-enabled devices.
   optional CastLogsProto cast_logs = 12;
 
   // Memory leak reports generated since the last UMA upload.
   repeated MemoryLeakReportProto memory_leak_report = 13;
 }