Factor out NetworkID and caching mechanism from n_q_e.{h,cc}

net/nqe/network_quality_observation_source.h

Index: net/nqe/network_quality_observation_source.h
diff --git a/net/nqe/network_quality_observation_source.h b/net/nqe/network_quality_observation_source.h
index da64c6766d18fef192d18d2911bfcb5bf21a564f..c1614027f277a84d25946ef31ca073e51bb0e528 100644
--- a/net/nqe/network_quality_observation_source.h
+++ b/net/nqe/network_quality_observation_source.h
@@ -32,7 +32,9 @@ enum NetworkQualityObservationSource {
   NETWORK_QUALITY_OBSERVATION_SOURCE_DEFAULT_FROM_PLATFORM,
 
   // The observation came from a Chromium-external source.
-  NETWORK_QUALITY_OBSERVATION_SOURCE_EXTERNAL_ESTIMATE
+  NETWORK_QUALITY_OBSERVATION_SOURCE_EXTERNAL_ESTIMATE,
+
+  NETWORK_QUALITY_OBSERVATION_SOURCE_MAX,

[RyanSturm, 2016/07/12 18:45:38]

This seems unrelated. Not worth its own CL, but it's confusing that it is part
of this CL.

[tbansal1, 2016/07/12 19:40:19]

Acknowledged.

 };
 
 }  // namespace net