Add chrome.power extension API.

chrome/browser/extensions/api/power/power_api_manager.cc

+// Copyright (c) 2013 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 "base/bind.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(api::power::Level level) {
+  switch (level) {
+    case api::power::LEVEL_SYSTEM:
+      return content::PowerSaveBlocker::kPowerSaveBlockPreventAppSuspension;
+    case api::power::LEVEL_DISPLAY:  // fallthrough
+    case api::power::LEVEL_NONE:
+      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,
+                                 api::power::Level level) {
+  extension_levels_[extension_id] = level;
+  UpdatePowerSaveBlocker();
+}
+
+void PowerApiManager::RemoveRequest(const std::string& extension_id) {
+  extension_levels_.erase(extension_id);
+  UpdatePowerSaveBlocker();
+}
+
+void PowerApiManager::SetCreateBlockerFunctionForTesting(
+    CreateBlockerFunction function) {
+  create_blocker_function_ = function;
+  if (create_blocker_function_.is_null())
+    create_blocker_function_ = base::Bind(&content::PowerSaveBlocker::Create);

[not at google - send to devlin, 2013/03/20 00:25:50]

if you like ternary

[Daniel Erat, 2013/03/20 00:47:46]

Done.

+}
+
+void PowerApiManager::Observe(int type,
+                              const content::NotificationSource& source,
+                              const content::NotificationDetails& details) {
+  switch (type) {
+    case chrome::NOTIFICATION_EXTENSION_UNLOADED:
+      RemoveRequest(content::Details<extensions::UnloadedExtensionInfo>(
+          details)->extension->id());
+      UpdatePowerSaveBlocker();
+      break;
+    case chrome::NOTIFICATION_APP_TERMINATING:
+      power_save_blocker_.reset();
+      break;
+    default:
+      NOTREACHED() << "Unexpected notification " << type;
+  }
+}
+
+PowerApiManager::PowerApiManager()
+    : create_blocker_function_(base::Bind(&content::PowerSaveBlocker::Create)),
+      current_level_(api::power::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();
+    return;
+  }
+
+  api::power::Level new_level = api::power::LEVEL_SYSTEM;
+  for (ExtensionLevelMap::const_iterator it = extension_levels_.begin();
+       it != extension_levels_.end(); ++it) {
+    if (it->second == api::power::LEVEL_DISPLAY)
+      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_ || new_level != current_level_) {
+    content::PowerSaveBlocker::PowerSaveBlockerType type =
+        LevelToPowerSaveBlockerType(new_level);
+    scoped_ptr<content::PowerSaveBlocker> new_blocker(
+        create_blocker_function_.Run(type, kPowerSaveBlockerReason));
+    power_save_blocker_.swap(new_blocker);
+    current_level_ = new_level;
+  }
+}
+
+}  // namespace extensions