Define DNS statistic data atom in atoms.proto file

Test: run runtests.sh, make sure no missing test and get all pass
      run /out/host/linux-x86/bin/statsd_testdrive 103
      Got following metric data dump:pass for local test
Bug: 119862317

Change-Id: I691e46ffe4cb30696d35018032d4a7f7628045d9
diff --git a/cmds/statsd/src/atoms.proto b/cmds/statsd/src/atoms.proto
index bdcdc536..fd62843 100644
--- a/cmds/statsd/src/atoms.proto
+++ b/cmds/statsd/src/atoms.proto
@@ -172,6 +172,7 @@
         WifiEnabledStateChanged wifi_enabled_state_changed = 113;
         WifiRunningStateChanged wifi_running_state_changed = 114;
         AppCompacted app_compacted = 115;
+        NetworkDnsEventReported network_dns_event_Reported = 116;
     }
 
     // Pulled events will start at field 10000.
@@ -3712,3 +3713,51 @@
   // The process state at the time of compaction.
   optional android.app.ProcessStateEnum process_state = 16 [default = PROCESS_STATE_UNKNOWN];
 }
+
+/**
+ * Logs the latency period(in microseconds) and the return code of
+ * the DNS(Domain Name System) lookups.
+ * These 4 methods(GETADDRINFO,GETHOSTBYNAME,GETHOSTBYADDR,RES_NSEND)
+ * to get info(address or hostname) from DNS server(or DNS cache).
+ * Logged from:
+ *   /system/netd/server/DnsProxyListener.cpp
+ */
+message NetworkDnsEventReported {
+    // The types of the DNS lookups, as defined in
+    //system/netd/server/binder/android/net/metrics/INetdEventListener.aidl
+    enum EventType {
+        EVENT_UNKNOWN = 0;
+        EVENT_GETADDRINFO = 1;
+        EVENT_GETHOSTBYNAME = 2;
+        EVENT_GETHOSTBYADDR = 3;
+        EVENT_RES_NSEND = 4;
+    }
+    optional EventType event_type = 1;
+
+    // The return value of the DNS resolver for each DNS lookups.
+    //bionic/libc/include/netdb.h
+    //system/netd/resolv/include/netd_resolv/resolv.h
+    enum ReturnCode {
+        EAI_NOERR = 0;
+        EAI_ADDRFAMILY = 1;
+        EAI_AGAIN = 2;
+        EAI_BADFLAGS = 3;
+        EAI_FAIL = 4;
+        EAI_FAMILY = 5;
+        EAI_MEMORY = 6;
+        EAI_NODATA = 7;
+        EAI_NONAME = 8;
+        EAI_SERVICE = 9;
+        EAI_SOCKTYPE = 10;
+        EAI_SYSTEM = 11;
+        EAI_BADHINTS = 12;
+        EAI_PROTOCOL = 13;
+        EAI_OVERFLOW = 14;
+        RESOLV_TIMEOUT = 255;
+        EAI_MAX = 256;
+    }
+    optional ReturnCode return_code = 2;
+
+    // The latency period(in microseconds) it took for this DNS lookup to complete.
+    optional int32 latency_micros = 3;
+}