Revert of [Contextual Search] Remove opt-in code.

chrome/browser/search/contextual_search_promo_source_android.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_SEARCH_CONTEXTUAL_SEARCH_PROMO_SOURCE_ANDROID_H_
+#define CHROME_BROWSER_SEARCH_CONTEXTUAL_SEARCH_PROMO_SOURCE_ANDROID_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "content/public/browser/url_data_source.h"
+
+// Serves HTML for displaying the contextual search first-run promo.
+class ContextualSearchPromoSourceAndroid : public content::URLDataSource {
+ public:
+  ContextualSearchPromoSourceAndroid();
+  ~ContextualSearchPromoSourceAndroid() override;
+
+ protected:
+  // Overridden from content::URLDataSource:
+  void StartDataRequest(
+      const std::string& path_and_query,
+      int render_process_id,
+      int render_frame_id,
+      const content::URLDataSource::GotDataCallback& callback) override;
+  std::string GetSource() const override;
+  std::string GetMimeType(const std::string& path_and_query) const override;
+  bool ShouldDenyXFrameOptions() const override;
+  bool ShouldAddContentSecurityPolicy() const override;
+
+  // Sends unmodified resource bytes.
+  void SendResource(
+      int resource_id,
+      const content::URLDataSource::GotDataCallback& callback);
+
+  // Sends the config JS resource.
+  void SendConfigResource(
+      const content::URLDataSource::GotDataCallback& callback);
+
+  // Sends HTML with localized strings.
+  void SendHtmlWithStrings(
+    const content::URLDataSource::GotDataCallback& callback);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ContextualSearchPromoSourceAndroid);
+};
+
+#endif  // CHROME_BROWSER_SEARCH_CONTEXTUAL_SEARCH_PROMO_SOURCE_ANDROID_H_