chromeos: Implement PowerSaveBlocker.

content/browser/power_save_blocker_chromeos.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 "content/browser/power_save_blocker.h"
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "chromeos/power/power_state_override.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+
+class PowerSaveBlocker::Delegate
+    : public base::RefCountedThreadSafe<PowerSaveBlocker::Delegate> {
+ public:
+  Delegate(PowerSaveBlockerType type) : type_(type) {}
+
+  // Creates a PowerStateOverride object to override the default power
+  // management behavior.
+  void ApplyBlock() {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+    chromeos::PowerStateOverride::Mode mode =
+        chromeos::PowerStateOverride::BLOCK_SYSTEM_SUSPEND;
+    switch (type_) {
+      case kPowerSaveBlockPreventAppSuspension:
+        mode = chromeos::PowerStateOverride::BLOCK_SYSTEM_SUSPEND;
+        break;
+      case kPowerSaveBlockPreventDisplaySleep:
+        mode = chromeos::PowerStateOverride::BLOCK_DISPLAY_SLEEP;
+        break;
+      default:
+        NOTREACHED() << "Unhandled block type " << type_;
+    }
+    override_.reset(new chromeos::PowerStateOverride(mode));
+  }
+
+  // Resets the previously-created PowerStateOverride object.
+  void RemoveBlock() {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+    override_.reset();
+  }
+
+ private:
+  friend class base::RefCountedThreadSafe<Delegate>;
+  virtual ~Delegate() {}
+
+  PowerSaveBlockerType type_;
+
+  scoped_ptr<chromeos::PowerStateOverride> override_;
+
+  DISALLOW_COPY_AND_ASSIGN(Delegate);
+};
+
+PowerSaveBlocker::PowerSaveBlocker(PowerSaveBlockerType type,
+                                   const std::string& reason)
+    : delegate_(new Delegate(type)) {
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                          base::Bind(&Delegate::ApplyBlock, delegate_));
+}
+
+PowerSaveBlocker::~PowerSaveBlocker() {
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                          base::Bind(&Delegate::RemoveBlock, delegate_));
+}
+
+}  // namespace content