Add logging for slow device events, limit network UI update rate

ash/system/chromeos/network/tray_network_state_observer.cc

Index: ash/system/chromeos/network/tray_network_state_observer.cc
diff --git a/ash/system/chromeos/network/tray_network_state_observer.cc b/ash/system/chromeos/network/tray_network_state_observer.cc
index 4239be295bbdc7a8d52beb56e91caa4608058cfe..8ec157a6f341656ba56ff27118a79f9fccafe4b5 100644
--- a/ash/system/chromeos/network/tray_network_state_observer.cc
+++ b/ash/system/chromeos/network/tray_network_state_observer.cc
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/location.h"
+#include "chromeos/device_event_log.h"
 #include "chromeos/network/network_state.h"
 #include "chromeos/network/network_state_handler.h"
 #include "third_party/cros_system_api/dbus/service_constants.h"
@@ -15,37 +16,43 @@
 
 using chromeos::NetworkHandler;
 
+namespace {
+
+const int kUpdateFrequencyMs = 1000;
+
+}  // namespace
+
 namespace ash {
 
 TrayNetworkStateObserver::TrayNetworkStateObserver(Delegate* delegate)
-    : delegate_(delegate) {
+    : delegate_(delegate), purge_icons_(false) {
   if (NetworkHandler::IsInitialized()) {
-    NetworkHandler::Get()->network_state_handler()->AddObserver(
-        this, FROM_HERE);
+    NetworkHandler::Get()->network_state_handler()->AddObserver(this,
+                                                                FROM_HERE);
   }
 }
 
 TrayNetworkStateObserver::~TrayNetworkStateObserver() {
   if (NetworkHandler::IsInitialized()) {
-    NetworkHandler::Get()->network_state_handler()->RemoveObserver(
-        this, FROM_HERE);
+    NetworkHandler::Get()->network_state_handler()->RemoveObserver(this,
+                                                                   FROM_HERE);
   }
 }
 
 void TrayNetworkStateObserver::NetworkListChanged() {
-  delegate_->NetworkStateChanged(true);
-  ui::network_icon::PurgeNetworkIconCache();
+  purge_icons_ = true;
+  SignalUpdate();
 }
 
 void TrayNetworkStateObserver::DeviceListChanged() {
-  delegate_->NetworkStateChanged(false);
+  SignalUpdate();
 }
 
 // Any change to the Default (primary connected) network, including Strength
 // changes, should trigger a NetworkStateChanged update.
 void TrayNetworkStateObserver::DefaultNetworkChanged(
     const chromeos::NetworkState* network) {
-  delegate_->NetworkStateChanged(true);
+  SignalUpdate();
 }
 
 // Any change to the Connection State should trigger a NetworkStateChanged
@@ -53,7 +60,7 @@ void TrayNetworkStateObserver::DefaultNetworkChanged(
 // connected.
 void TrayNetworkStateObserver::NetworkConnectionStateChanged(
     const chromeos::NetworkState* network) {
-  delegate_->NetworkStateChanged(true);
+  SignalUpdate();
 }
 
 // This tracks Strength and other property changes for all networks. It will
@@ -61,13 +68,22 @@ void TrayNetworkStateObserver::NetworkConnectionStateChanged(
 // changes.
 void TrayNetworkStateObserver::NetworkPropertiesUpdated(
     const chromeos::NetworkState* network) {
-  if (network ==
-      NetworkHandler::Get()->network_state_handler()->DefaultNetwork()) {
-    // Trigger NetworkStateChanged in case the Strength property of the
-    // Default network changed.
-    delegate_->NetworkStateChanged(true);
+  SignalUpdate();
+}
+
+void TrayNetworkStateObserver::SignalUpdate() {
+  if (timer_.IsRunning())
+    return;
+  timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(kUpdateFrequencyMs),
+               this, &TrayNetworkStateObserver::SendNetworkStateChanged);
+}
+
+void TrayNetworkStateObserver::SendNetworkStateChanged() {
+  delegate_->NetworkStateChanged();
+  if (purge_icons_) {
+    ui::network_icon::PurgeNetworkIconCache();
+    purge_icons_ = false;
   }
-  delegate_->NetworkServiceChanged(network);
 }
 
 }  // namespace ash