Bluetooth: gather usage metrics

device/bluetooth/bluetooth_adapter_experimental_chromeos.cc

Index: device/bluetooth/bluetooth_adapter_experimental_chromeos.cc
diff --git a/device/bluetooth/bluetooth_adapter_experimental_chromeos.cc b/device/bluetooth/bluetooth_adapter_experimental_chromeos.cc
index 50516906f994fbcf0a35eede1f98bf03f15c469d..6a282f3c220e7227e6364c36baa7555f7728fb7f 100644
--- a/device/bluetooth/bluetooth_adapter_experimental_chromeos.cc
+++ b/device/bluetooth/bluetooth_adapter_experimental_chromeos.cc
@@ -8,6 +8,7 @@
 
 #include "base/bind.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/experimental_bluetooth_adapter_client.h"
 #include "chromeos/dbus/experimental_bluetooth_device_client.h"
@@ -253,6 +254,19 @@ void BluetoothAdapterExperimentalChromeOS::DevicePropertyChanged(
       property_name == properties->connected.name() ||
       property_name == properties->uuids.name())
     NotifyDeviceChanged(device_chromeos);
+
+  // UMA connection counting
+  if (property_name == properties->connected.name()) {
+    int count = 0;
+
+    for (DevicesMap::iterator iter = devices_.begin();
+         iter != devices_.end(); ++iter) {
+      if (iter->second->IsConnected())
+        ++count;
+    }
+
+    UMA_HISTOGRAM_COUNTS_100("Bluetooth.ConnectedDeviceCount", count);
+  }
 }
 
 void BluetoothAdapterExperimentalChromeOS::InputPropertyChanged(