Add chrome.power extension API.

chrome/browser/extensions/api/power/power_api_manager.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 "chrome/browser/extensions/api/power/power_api_manager.h"
+
+#include "chrome/common/chrome_notification_types.h"
+#include "chrome/common/extensions/extension.h"
+#include "content/public/browser/notification_service.h"
+
+namespace extensions {
+
+namespace {
+
+const char kPowerSaveBlockerReason[] = "extension";
+
+content::PowerSaveBlocker::PowerSaveBlockerType
+LevelToPowerSaveBlockerType(PowerApiManager::Level level) {
+  switch (level) {
+    case PowerApiManager::LEVEL_SYSTEM:
+      return content::PowerSaveBlocker::kPowerSaveBlockPreventAppSuspension;
+    case PowerApiManager::LEVEL_DISPLAY:
+      return content::PowerSaveBlocker::kPowerSaveBlockPreventDisplaySleep;
+  }
+  NOTREACHED() << "Unhandled level " << level;
+  return content::PowerSaveBlocker::kPowerSaveBlockPreventDisplaySleep;
+}
+
+}  // namespace
+
+// static
+PowerApiManager* PowerApiManager::GetInstance() {
+  return Singleton<PowerApiManager>::get();
+}
+
+void PowerApiManager::AddRequest(const std::string& extension_id, Level level) {
+  extension_levels_[extension_id] = level;
+  UpdatePowerSaveBlocker();
+}
+
+void PowerApiManager::RemoveRequest(const std::string& extension_id) {
+  extension_levels_.erase(extension_id);
+  UpdatePowerSaveBlocker();
+}
+
+void PowerApiManager::Observe(int type,
+                              const content::NotificationSource& source,
+                              const content::NotificationDetails& details) {
+  if (type == chrome::NOTIFICATION_EXTENSION_UNLOADED) {

[not at google - send to devlin, 2013/03/19 21:16:39]

prefer switch

[Daniel Erat, 2013/03/19 23:39:38]

Done.

+    RemoveRequest(content::Details<extensions::UnloadedExtensionInfo>(details)->
+                  extension->id());
+    UpdatePowerSaveBlocker();
+  } else if (type == chrome::NOTIFICATION_APP_TERMINATING) {
+    power_save_blocker_.reset();
+  } else {
+    NOTREACHED() << "Unexpected notification " << type;
+  }
+}
+
+PowerApiManager::PowerApiManager() : current_level_(LEVEL_SYSTEM) {
+  registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED,
+                  content::NotificationService::AllSources());
+  registrar_.Add(this, chrome::NOTIFICATION_APP_TERMINATING,
+                 content::NotificationService::AllSources());
+}
+
+PowerApiManager::~PowerApiManager() {}
+
+void PowerApiManager::UpdatePowerSaveBlocker() {
+  if (extension_levels_.empty()) {
+    power_save_blocker_.reset();

[not at google - send to devlin, 2013/03/19 21:16:39]

nit: early return

[Daniel Erat, 2013/03/19 23:39:38]

Done.

+  } else {
+    Level new_level = LEVEL_SYSTEM;
+    for (ExtensionLevelMap::const_iterator it = extension_levels_.begin();
+         it != extension_levels_.end(); ++it) {
+      if (it->second > new_level)
+        new_level = it->second;
+    }
+
+    // If the level changed and we need to create a new blocker, do a swap
+    // to ensure that there isn't a brief period where power management is
+    // unblocked.
+    if (!power_save_blocker_.get() || new_level != current_level_) {

[not at google - send to devlin, 2013/03/19 21:16:39]

.get() unnecessary

[Daniel Erat, 2013/03/19 23:39:38]

Done.

+      content::PowerSaveBlocker::PowerSaveBlockerType type =
+          LevelToPowerSaveBlockerType(new_level);
+      scoped_ptr<content::PowerSaveBlocker> new_blocker(
+          create_blocker_function_.get() ?

[not at google - send to devlin, 2013/03/19 21:16:39]

.get() unnecessary

[Daniel Erat, 2013/03/19 23:39:38]

Done.

+          create_blocker_function_->Run(type, kPowerSaveBlockerReason) :
+          content::PowerSaveBlocker::Create(type, kPowerSaveBlockerReason));

[not at google - send to devlin, 2013/03/19 21:16:39]

could you initialize create_blocker_function_ to
content::PowerSaveBlocker::Create? then you wouldn't need this extra logic at
all.

[Daniel Erat, 2013/03/19 23:39:38]

Done.

+      power_save_blocker_.swap(new_blocker);
+      current_level_ = new_level;
+    }
+  }
+}
+
+}  // namespace extensions