First step in enabling creating tabs without an Activity on Android.

chrome/browser/android/service_tab_launcher.h

Index: chrome/browser/android/service_tab_launcher.h
diff --git a/chrome/browser/android/service_tab_launcher.h b/chrome/browser/android/service_tab_launcher.h
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+// Copyright 2015 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_ANDROID_SERVICE_TAB_LAUNCHER_H_
+#define CHROME_BROWSER_ANDROID_SERVICE_TAB_LAUNCHER_H_
+
+#include "base/android/jni_android.h"
+#include "base/callback_forward.h"
+#include "base/memory/singleton.h"
+
+namespace content {
+class BrowserContext;
+struct OpenURLParams;
+class WebContents;
+}
+
+namespace chrome {
+namespace android {
+
+// Launcher for creating new tabs on Android from a background service, where
+// there may not necessarily be an Activity or a tab model at all.
+class ServiceTabLauncher {
+ public:
+  // Returns the singleton instance of the service tab launcher.
+  static ServiceTabLauncher* GetInstance();
+
+  // Launches a new tab when we're in a Service rather than in an Activity.
+  // |callback| will be invoked with the resulting content::WebContents* when
+  // the tab is avialable. This method must only be called from the UI thread.
+  void LaunchTab(content::BrowserContext* browser_context,
+                 const content::OpenURLParams& params,
+                 const base::Callback<void(content::WebContents*)>& callback);
+
+  static bool RegisterServiceTabLauncher(JNIEnv* env);
+
+ private:
+  friend struct DefaultSingletonTraits<ServiceTabLauncher>;
+
+  ServiceTabLauncher();
+  ~ServiceTabLauncher();
+
+  base::android::ScopedJavaGlobalRef<jobject> java_object_;
+
+  DISALLOW_COPY_AND_ASSIGN(ServiceTabLauncher);
+};
+
+}  // namespace android
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_ANDROID_SERVICE_TAB_LAUNCHER_H_