Bluetooth: gather usage metrics

chrome/browser/metrics/metrics_log.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines a set of user experience metrics data recorded by
 // the MetricsService.  This is the unit of data that is sent to the server.
 
 #ifndef CHROME_BROWSER_METRICS_METRICS_LOG_H_
 #define CHROME_BROWSER_METRICS_METRICS_LOG_H_
 
@@ skipping 12 matching lines @@
 
 struct AutocompleteLog;
 class MetricsNetworkObserver;
 class PrefService;
 class PrefRegistrySimple;
 
 namespace base {
 class DictionaryValue;
 }
 
+namespace device {
+class BluetoothAdapter;
+}
+
 namespace tracked_objects {
 struct ProcessDataSnapshot;
 }
 
 namespace chrome_variations {
 struct ActiveGroupId;
 }
 
 namespace webkit {
 struct WebPluginInfo;
@@ skipping 139 matching lines @@
 
   // Writes metrics for the profile identified by key. This writes all
   // key/value pairs in profile_metrics.
   void WriteProfileMetrics(const std::string& key,
                            const base::DictionaryValue& profile_metrics);
 
   // Writes info about the Google Update install that is managing this client.
   // This is a no-op if called on a non-Windows platform.
   void WriteGoogleUpdateProto(const GoogleUpdateMetrics& google_update_metrics);
 
+  // Writes info about paired Bluetooth devices on this system.
+  // This is a no-op if called on a non-Chrome OS platform.
+  void WriteBluetoothProto(metrics::SystemProfileProto::Hardware* hardware,
+                           scoped_refptr<device::BluetoothAdapter> adapter);
+
   // Observes network state to provide values for SystemProfile::Network.
   MetricsNetworkObserver network_observer_;
 
 #if defined(OS_CHROMEOS)
   metrics::PerfProvider perf_provider_;
 #endif
 
+  // Weak pointer factory for generating 'this' pointers that might live longer
+  // than we do.
+  // Note: This should remain the last member so it'll be destroyed and
+  // invalidate its weak pointers before any other members are destroyed.

[Ilya Sherman, 2013/04/23 00:09:43]

Hmm, why is the destruction order important?  Is there some particular other
member that relies on this destruction order?

[keybuk, 2013/04/23 00:41:42]

comment copied from other code ;) removed

+  base::WeakPtrFactory<MetricsLog> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(MetricsLog);
 };
 
 #endif  // CHROME_BROWSER_METRICS_METRICS_LOG_H_