Add histogram to track network-related platform notifications received

by QUIC users. Those notifications are:
- NetworkConnected
- NetworkMadeDefault
- NetworkDisconnected
- NetworkSoonToDisconnect
- IpAddressChanged

Bug: 765436
Change-Id: I6205540d9dbbff63010a40ef06febfede2257bef
Reviewed-on: https://chromium-review.googlesource.com/687878Reviewed-by: Ryan Hamilton <rch@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504835}

net/quic/chromium/quic_stream_factory.cc

@@ -181,6 +181,12 @@ void HistogramMigrationStatus(enum QuicConnectionMigrationStatus status) {
                             MIGRATION_STATUS_MAX);
 }
 
+void LogPlatformNotificationInHistogram(
+    enum QuicPlatformNotification notification) {
+  UMA_HISTOGRAM_ENUMERATION("Net.QuicSession.PlatformNotification",
+                            notification, NETWORK_NOTIFICATION_MAX);
+}
+
 void SetInitialRttEstimate(base::TimeDelta estimate,
                            enum InitialRttEstimateSource source,
                            QuicConfig* config) {
@@ -1170,6 +1176,7 @@ void QuicStreamFactory::ClearCachedStatesInCryptoConfig(
 }
 
 void QuicStreamFactory::OnIPAddressChanged() {
+  LogPlatformNotificationInHistogram(NETWORK_IP_ADDRESS_CHANGED);
   // Do nothing if connection migration is in use.
   if (migrate_sessions_on_network_change_)
     return;
@@ -1178,6 +1185,7 @@ void QuicStreamFactory::OnIPAddressChanged() {
 }
 
 void QuicStreamFactory::OnNetworkConnected(NetworkHandle network) {
+  LogPlatformNotificationInHistogram(NETWORK_CONNECTED);
   if (!migrate_sessions_on_network_change_)
     return;
   ScopedConnectionMigrationEventLog scoped_event_log(net_log_,
@@ -1192,6 +1200,7 @@ void QuicStreamFactory::OnNetworkConnected(NetworkHandle network) {
 }
 
 void QuicStreamFactory::OnNetworkMadeDefault(NetworkHandle network) {
+  LogPlatformNotificationInHistogram(NETWORK_MADE_DEFAULT);
   if (most_recent_path_degrading_timestamp_ != base::TimeTicks()) {
     if (most_recent_network_disconnected_timestamp_ != base::TimeTicks()) {
       // NetworkDiscconected happens before NetworkMadeDefault, the platform
@@ -1225,6 +1234,7 @@ void QuicStreamFactory::OnNetworkMadeDefault(NetworkHandle network) {
 }
 
 void QuicStreamFactory::OnNetworkDisconnected(NetworkHandle network) {
+  LogPlatformNotificationInHistogram(NETWORK_DISCONNECTED);
   if (most_recent_path_degrading_timestamp_ != base::TimeTicks()) {
     most_recent_network_disconnected_timestamp_ = base::TimeTicks::Now();
     base::TimeDelta degrading_duration =
@@ -1247,7 +1257,9 @@ void QuicStreamFactory::OnNetworkDisconnected(NetworkHandle network) {
 
 // This method is expected to only be called when migrating from Cellular to
 // WiFi on Android, and should always be preceded by OnNetworkMadeDefault().
-void QuicStreamFactory::OnNetworkSoonToDisconnect(NetworkHandle network) {}
+void QuicStreamFactory::OnNetworkSoonToDisconnect(NetworkHandle network) {
+  LogPlatformNotificationInHistogram(NETWORK_SOON_TO_DISCONNECT);
+}
 
 NetworkHandle QuicStreamFactory::FindAlternateNetwork(
     NetworkHandle old_network) {

net/quic/chromium/quic_stream_factory.h

@@ -101,6 +101,15 @@ enum QuicConnectionMigrationStatus {
   MIGRATION_STATUS_MAX
 };
 
+enum QuicPlatformNotification {
+  NETWORK_CONNECTED,
+  NETWORK_MADE_DEFAULT,
+  NETWORK_DISCONNECTED,
+  NETWORK_SOON_TO_DISCONNECT,
+  NETWORK_IP_ADDRESS_CHANGED,
+  NETWORK_NOTIFICATION_MAX
+};
+
 // Encapsulates a pending request for a QuicHttpStream.
 // If the request is still pending when it is destroyed, it will
 // cancel the request with the factory.

tools/metrics/histograms/enums.xml

@@ -32815,6 +32815,14 @@ from previous Chrome versions.
   <int value="2" label="REF_COUNT"/>
 </enum>
 
+<enum name="QuicPlatformNotification">
+  <int value="0" label="NETWORK_CONNECTED"/>
+  <int value="1" label="NETWORK_MADE_DEFAULT"/>
+  <int value="2" label="NETWORK_DISCONNECTED"/>
+  <int value="3" label="NETWORK_SOON_TO_DISCONNECT"/>
+  <int value="4" label="NETWORK_IP_ADDRESS_CHANGED"/>
+</enum>
+
 <enum name="QuicRejectReasons">
   <int value="1" label="CLIENT_NONCE_UNKNOWN_FAILURE"/>
   <int value="2" label="CLIENT_NONCE_INVALID_FAILURE"/>

tools/metrics/histograms/histograms.xml

@@ -42535,6 +42535,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Net.QuicSession.PlatformNotification"
+    enum="QuicPlatformNotification">
+  <owner>zhongyi@chromium.org</owner>
+  <summary>
+    The platform notification received by QUIC when network change happens.
+  </summary>
+</histogram>
+
 <histogram name="Net.QuicSession.PreferAesGcm" enum="BooleanPreferred">
   <owner>rch@chromium.org</owner>
   <summary>