Relanding the language detection.

chrome/browser/cld_helper.h

+// Copyright (c) 2009 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_CLD_HELPER_H_
+#define CHROME_BROWSER_CLD_HELPER_H_
+
+#include <string>
+
+#include "base/ref_counted.h"
+
+class TabContents;
+
+// The CLDHelper class detects the language of a page, using the toolbar CLD
+// library. (CLD stands for Compact Language Detection.)
+// It should be created and the detection process started on the UI thread.
+// The detection happens on the file thread and
+// TabContents::PageLanguageDetected() is then called on the associated
+// TabContents when the language has been detected.
+class CLDHelper : public base::RefCountedThreadSafe<CLDHelper> {
+ public:
+  // |tab_contents| should reference the TabContents the page is related to.
+  // |renderer_process_id|, |page_id| and |page_contents| are the id of the
+  // render process, the id and contents of the page the language is queried.
+  CLDHelper(TabContents* tab_contents,
+            int renderer_process_id,
+            int page_id,
+            const std::wstring& page_content);
+
+  // Starts the process of detecting the language of the page.
+  void DetectLanguage();
+
+  // Cancel any pending language detection, meaning that the TabContents will
+  // not be notified.
+  // This should be on the same thread as DetectLanguage was called.
+  void CancelLanguageDetection();
+
+  int renderer_process_id() const { return renderer_process_id_; }
+
+  int page_id() const { return page_id_; }
+
+  std::string language() const { return language_; }
+
+ private:
+  // Private because the class is ref counted.
+  friend class base::RefCountedThreadSafe<CLDHelper>;
+  ~CLDHelper() {}
+
+  // Performs the actual work of detecting the language.
+  void DoDetectLanguage();
+
+  // Invoked on the UI thread once the language has been detected.
+  void DetectionDone();
+
+  // The tab contents for which the language is being detected.
+  TabContents* tab_contents_;
+
+  // The id for the render process the page belongs to.
+  int renderer_process_id_;
+
+  // The id and content of the page for which the language is being detected.
+  int page_id_;
+  std::wstring page_content_;
+
+  // The language that was detected.
+  std::string language_;
+
+  DISALLOW_COPY_AND_ASSIGN(CLDHelper);
+};
+
+#endif  // CHROME_BROWSER_CLD_HELPER_H_
+