Clarify AndroidStatusFetcher documentation

chrome/browser/chromeos/policy/device_status_collector.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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_POLICY_DEVICE_STATUS_COLLECTOR_H_
 #define CHROME_BROWSER_CHROMEOS_POLICY_DEVICE_STATUS_COLLECTOR_H_
 
 #include <stdint.h>
 
 #include <deque>
@@ skipping 50 matching lines @@
 
   // Reads CPU temperatures from /sys/class/hwmon/hwmon*/temp*_input and
   // appropriate labels from /sys/class/hwmon/hwmon*/temp*_label.
   using CPUTempFetcher =
       base::Callback<std::vector<enterprise_management::CPUTempInfo>()>;
 
   // Passed into asynchronous mojo interface for communicating with Android.
   using AndroidStatusReceiver =
       base::Callback<void(const std::string&, const std::string&)>;
   // Calls the enterprise reporting mojo interface, passing over the
-  // AndroidStatusReceiver.
+  // AndroidStatusReceiver. Returns false if the mojo interface isn't available,
+  // in which case no asynchronous query is emitted and the android status query
+  // fails synchronously. The |AndroidStatusReceiver| is not called in this
+  // case.
   using AndroidStatusFetcher =
       base::Callback<bool(const AndroidStatusReceiver&)>;
 
   // Called in the UI thread after the device and session status have been
   // collected asynchronously in GetDeviceAndSessionStatusAsync. Null pointers
   // indicate errors or that device or session status reporting is disabled.
   using StatusCallback = base::Callback<void(
       std::unique_ptr<enterprise_management::DeviceStatusReportRequest>,
       std::unique_ptr<enterprise_management::SessionStatusReportRequest>)>;
 
   // Constructor. Callers can inject their own VolumeInfoFetcher,
   // CPUStatisticsFetcher and CPUTempFetcher. These callbacks are executed on
   // Blocking Pool. A null callback can be passed for either parameter, to use

[Andrew T Wilson (Slow), 2016/11/28 10:37:20]

"either parameter" is out of date - let's update this since there's more than 2
params now :)

   // the default implementation.
   DeviceStatusCollector(
       PrefService* local_state,
       chromeos::system::StatisticsProvider* provider,
       const VolumeInfoFetcher& volume_info_fetcher,
       const CPUStatisticsFetcher& cpu_statistics_fetcher,
       const CPUTempFetcher& cpu_temp_fetcher,
       const AndroidStatusFetcher& android_status_fetcher);
   virtual ~DeviceStatusCollector();
 
@@ skipping 190 matching lines @@
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<DeviceStatusCollector> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DeviceStatusCollector);
 };
 
 }  // namespace policy
 
 #endif  // CHROME_BROWSER_CHROMEOS_POLICY_DEVICE_STATUS_COLLECTOR_H_