Extend the capability of SystemMonitor to support watching storage free space change

base/system_monitor/system_monitor.cc

 // 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.
 
 #include "base/system_monitor/system_monitor.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 21 matching lines @@
     : device_id(id),
       name(device_name),
       location(device_location) {
 }
 
 SystemMonitor::SystemMonitor()
     : power_observer_list_(new ObserverListThreadSafe<PowerObserver>()),
       devices_changed_observer_list_(
           new ObserverListThreadSafe<DevicesChangedObserver>()),
       battery_in_use_(false),
-      suspended_(false) {
+      suspended_(false),
+      free_space_delegate_(NULL) {
   DCHECK(!g_system_monitor);
   g_system_monitor = this;
 
   DCHECK(MessageLoop::current());
 #if defined(ENABLE_BATTERY_MONITORING)
   delayed_battery_check_.Start(FROM_HERE,
       base::TimeDelta::FromMilliseconds(kDelayedBatteryCheckMs), this,
       &SystemMonitor::BatteryCheck);
 #endif  // defined(ENABLE_BATTERY_MONITORING)
 #if defined(OS_MACOSX)
@@ skipping 61 matching lines @@
 }
 
 void SystemMonitor::ProcessRemovableStorageDetached(const std::string& id) {
   RemovableStorageMap::iterator it = removable_storage_map_.find(id);
   if (it == removable_storage_map_.end())
     return;
   removable_storage_map_.erase(it);
   NotifyRemovableStorageDetached(id);
 }
 
+void SystemMonitor::ProcessStorageFreeSpaceChanged(
+    const FilePath::StringType& path) {
+  DVLOG(1) << "Free Space Changing";
+  devices_changed_observer_list_->Notify(
+      &DevicesChangedObserver::OnStorageFreeSpaceChanged, path);
+}
+
+bool SystemMonitor::StartWatchingStorage(const FilePath::StringType& path) {
+  if (!free_space_delegate_)
+    return false;
+
+  // Try to start watching if the first one is requested.
+  if (watched_storages_.find(path) == watched_storages_.end() &&
+      !free_space_delegate_->StartWatchingStorage(path)) {
+    return false;
+  }
+
+  // The free space watcher has been started for the storage identifed by
+  // |path|.
+  watched_storages_.insert(path);
+  return true;
+}
+
+bool SystemMonitor::StopWatchingStorage(const FilePath::StringType& path) {
+  if (!free_space_delegate_)
+    return false;
+
+  watched_storages_.erase(path);
+
+  // Try to stop watching when the last one is erased.
+  if (watched_storages_.find(path) == watched_storages_.end() &&
+      !free_space_delegate_->StopWatchingStorage(path))
+    return false;
+
+  return true;
+}
+
 std::vector<SystemMonitor::RemovableStorageInfo>
 SystemMonitor::GetAttachedRemovableStorage() const {
   std::vector<RemovableStorageInfo> results;
   for (RemovableStorageMap::const_iterator it = removable_storage_map_.begin();
        it != removable_storage_map_.end();
        ++it) {
     results.push_back(it->second);
   }
   return results;
 }
@@ skipping 51 matching lines @@
 void SystemMonitor::NotifyResume() {
   DVLOG(1) << "Power Resuming";
   power_observer_list_->Notify(&PowerObserver::OnResume);
 }
 
 void SystemMonitor::BatteryCheck() {
   ProcessPowerMessage(SystemMonitor::POWER_STATE_EVENT);
 }
 
 }  // namespace base