Refactor language detection logic to allow non-static CLD data sources.

components/translate/content/browser/browser_cld_data_provider_factory.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 COMPONENTS_TRANSLATE_CONTENT_BROWSER_BROWSER_CLD_DATA_PROVIDER_FACTORY_H_
+#define COMPONENTS_TRANSLATE_CONTENT_BROWSER_BROWSER_CLD_DATA_PROVIDER_FACTORY_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/translate/content/browser/browser_cld_data_provider.h"
+
+namespace content {
+class WebContents;
+}
+
+namespace translate {
+
+// A factory for the Browser side of CLD Data Providers. The embedder should
+// set an instance as soon as feasible during startup. The browser process will
+// use this factory to create the one BrowserCldDataProvider for each render
+// view host in order to communicate with a RendererCldDataProvider in the
+// renderer process. For more information on the RendererCldDataProvider, see:
+//   ../renderer/renderer_cld_data_provider.h
+class BrowserCldDataProviderFactory {
+ public:
+  BrowserCldDataProviderFactory() {}
+  virtual ~BrowserCldDataProviderFactory() {}
+
+  // Create and return a new instance of a BrowserCldDataProvider. The default
+  // implementation of this method produces a no-op BrowserCldDataProvider that
+  // is suitable only when CLD data has been statically linked.
+  // Every invocation creates a new provider; the caller is responsible for
+  // deleting the object when it is no longer needed.
+  virtual scoped_ptr<BrowserCldDataProvider> CreateBrowserCldDataProvider(
+      content::WebContents* web_contents);
+
+  // Returns true if and only if the current instance for this process is not
+  // NULL.
+  static bool IsInitialized();
+
+  // Sets the default factory for this process, i.e. the factory to be used
+  // unless the embedder calls Set(BrowserCldDataProviderFactory*). This is the
+  // method that normal (i.e., non-test) Chromium code should use; embedders can
+  // and should use the unconditional Set(BrowserCldDataProviderFactory*) method
+  // instead. If a default factory has already been set, this method does
+  // nothing.
+  static void SetDefault(BrowserCldDataProviderFactory* instance);
+
+  // Unconditionally sets the factory for this process, overwriting any
+  // previously-configured default. Normal Chromium code should never use this
+  // method; it is provided for embedders to inject a factory from outside of
+  // the Chromium code base. Test code can also use this method to force the
+  // runtime to have a desired behavior.
+  static void Set(BrowserCldDataProviderFactory* instance);
+
+  // Returns the instance of the factory previously set by Set()/SetDefault().
+  // If no instance has been set, a default factory will be returned that
+  // produces no-op BrowserCldDataProviders as described by NewProvider(...)
+  // above.
+  static BrowserCldDataProviderFactory* Get();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BrowserCldDataProviderFactory);
+};
+
+}  // namespace translate
+
+#endif  // COMPONENTS_TRANSLATE_CONTENT_BROWSER_BROWSER_CLD_DATA_PROVIDER_FACTORY_H_