Add DiscoveryNetworkMonitor implementation

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index bdbb9a92d6c858069d783d92cd8da3121c16eced..6dd000da5b99211775bd7bb9a0084a98b8bfc723 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -89446,6 +89446,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="403" label="CLIPBOARD_ON_CLIPBOARD_DATA_CHANGED"/>
   <int value="404" label="VIRTUAL_KEYBOARD_PRIVATE_ON_KEYBOARD_CLOSED"/>
   <int value="405" label="FILE_MANAGER_PRIVATE_ON_APPS_UPDATED"/>
+  <int value="406" label="DIAL_ON_NETWORK_ID_CHANGED"/>
 </enum>
 
 <enum name="ExtensionFileWriteResult" type="int">
@@ -90659,6 +90660,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1161" label="AUDIO_SETMUTE"/>
   <int value="1162" label="AUDIO_GETDEVICES"/>
   <int value="1163" label="VIRTUALKEYBOARD_RESTRICTFEATURES"/>
+  <int value="1164" label="DIAL_GETNETWORKID"/>
 </enum>
 
 <enum name="ExtensionIconState" type="int">