Add the Copresence API.

chrome/browser/extensions/api/copresence/copresence_util.h

+// Copyright 2014 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_EXTENSIONS_API_COPRESENCE_COPRESENCE_UTIL_H_
+#define CHROME_BROWSER_EXTENSIONS_API_COPRESENCE_COPRESENCE_UTIL_H_
+
+namespace content {
+class BrowserContext;
+}
+
+namespace copresence {
+class CopresenceClient;
+class WhispernetClient;
+}
+
+namespace extensions {
+
+class CopresenceService;
+
+CopresenceService* GetCopresenceService(
+    content::BrowserContext* browser_context);
+
+copresence::CopresenceClient* GetCopresenceClient(
+    content::BrowserContext* browser_context);
+
+copresence::WhispernetClient* GetWhispernetClient(
+    content::BrowserContext* browser_context);
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_COPRESENCE_COPRESENCE_UTIL_H_