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

chrome/browser/translate/cld_data_harness_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 CHROME_BROWSER_TRANSLATE_CLD_DATA_HARNESS_FACTORY_H_
+#define CHROME_BROWSER_TRANSLATE_CLD_DATA_HARNESS_FACTORY_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/translate/cld_data_harness.h"
+
+namespace test {
+
+// Testing class that allows embedders to inject an arbitrary CldDataHarness
+// implementation into the runtime by defining a subclass of
+// CldDataHarnessFactory and setting the global instance of it with
+// Set(CldDataHarnessFactory*). Chromium code should use the factory instance
+// returned by Get() to obtain CldDataHarness instances.
+//
+// There is significant nuance to obtaining a CldDataHarness object at runtime.
+// For each of the "stock" CldDataSource implementations ("standalone",
+// "static" and "component"), a CldDataHarness implementation is available and
+// the default implementation of the CldDataHarnessFactory class knows how to
+// do the right thing; but embedders can provider entirely custom CldDataSource
+// implementations, and browser tests need to be able to use those data sources
+// correctly at test time. Embedders implement a subclass of
+// CldDataHarnessFactory and set it using Set(), below, to enable browser tests
+// to function as realistically as possible with the embedder's data source.
+class CldDataHarnessFactory {
+ public:
+  CldDataHarnessFactory() {}
+  virtual ~CldDataHarnessFactory() {}
+
+  // Create a new CldDataHarness.
+  // The default implementation returns a simple CldDataHarness, which is
+  // likely to be incorrect for most non-static CLD use cases.
+  virtual scoped_ptr<CldDataHarness> CreateCldDataHarness();
+
+  // Unconditionally sets the factory for this process, overwriting any
+  // previously-configured value. Open-source Chromium test code should almost
+  // never use this method; it is provided for embedders to inject a factory
+  // from outside of the Chromium code base. By default, the choice of which
+  // factory to use is based on the currently-configured CldDataSource when
+  // calling Get() (see below).
+  static void Set(CldDataHarnessFactory* instance);
+
+  // Returns the CldDataHarnessFactory instance previously set for the process,
+  // if one has been set; otherwise, if the currently configured CldDataSource
+  // is one of the available open-source types defined in CldDataSource, returns
+  // a compatible harness. Otherwise (e.g., no specific instance has been set
+  // and the CldDataSource is not one of the known open-source implementations),
+  // debug builds will crash while release builds will return a no-op harness.
+  static CldDataHarnessFactory* Get();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CldDataHarnessFactory);
+
+  // Fetch the global instance of the "static" factory that produces a harness
+  // suitable for use with the "static" CLD data source.
+  // Only use to call Set(CldDataHarnessFactory*).
+  static CldDataHarnessFactory* GetStaticDataHarnessFactory();
+
+  // Fetch the global instance of the "standalone" factory that produces a
+  // harness suitable for use with the "standalone" CLD data source.
+  // Only use to call Set(CldDataHarnessFactory*).
+  static CldDataHarnessFactory* GetStandaloneDataHarnessFactory();
+
+  // Fetch the global instance of the "component" factory that produces a
+  // harness suitable for use with the "component" CLD data source.
+  // Only use to call Set(CldDataHarnessFactory*).
+  static CldDataHarnessFactory* GetComponentDataHarnessFactory();
+};
+}  // namespace test
+
+#endif  // CHROME_BROWSER_TRANSLATE_CLD_DATA_HARNESS_FACTORY_H_