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 "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.
+  // TODO(andrewhayden) scoped_ptr?

[Andrew Hayden (chromium.org), 2014/11/10 14:06:35]

This still needs to be done, and it seems to make sense to hand it off as a
scoped_ptr, so do it!

+  virtual BrowserCldDataProvider* NewProvider(

[Takashi Toyoshima, 2014/11/06 14:34:29]

NewProvider() does not sound a consistent name with other factory classes. More
common name is better so that other developers are not surprised.

[Andrew Hayden (chromium.org), 2014/11/10 14:06:35]

I took a look at cs.chromium.org and tried to find some factories for reference:
https://code.google.com/p/chromium/codesearch#chromium/src/media/filters/stre...
https://code.google.com/p/chromium/codesearch#chromium/src/ash/accelerators/f...
https://code.google.com/p/chromium/codesearch#chromium/src/remoting/host/sess...
https://code.google.com/p/chromium/codesearch#chromium/src/sync/internal_api/...

It looks like there is some consensus that FooFactory.h declares a method called
either just "Create()" or "CreateFoo()", with "CreateFoo()" being dominant. I
will go with that naming scheme, but I think this goes against your comment in
CldDataHarnessFactory.h. As you have pointed out, consistency is good; so I will
stick with the CreateFoo() pattern unless you strongly object otherwise.

[Takashi Toyoshima, 2014/11/11 07:16:36]

I agreed to use CreateFoo() pattern.

+      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_