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

components/translate/content/common/cld_data_source.cc

+// 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.
+
+#include "components/translate/content/common/cld_data_source.h"
+
+#include "base/lazy_instance.h"
+
+namespace {
+
+// This is the global instance managed by Get/Set/SetDefault
+translate::CldDataSource* g_instance = NULL;
+
+// Global instances for the builtin data source types
+base::LazyInstance<translate::CldDataSource>::Leaky g_wrapped_static =
+    LAZY_INSTANCE_INITIALIZER;
+base::LazyInstance<translate::CldDataSource>::Leaky g_wrapped_standalone =
+    LAZY_INSTANCE_INITIALIZER;
+base::LazyInstance<translate::CldDataSource>::Leaky g_wrapped_component =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace translate {
+
+CldDataSource::CldDataSource() : m_cached_filepath(), m_file_lock() {
+}
+
+std::string CldDataSource::GetName() {
+  if (this == GetStaticDataSource()) return "static";
+  if (this == GetComponentDataSource()) return "component";
+  if (this == GetStandaloneDataSource()) return "standalone";
+  NOTREACHED() << "Subclass failed to override GetName()";
+  return "unknown";
+}
+
+void CldDataSource::SetCldDataFilePath(const base::FilePath& path) {
+  DCHECK(this == GetComponentDataSource() ||
+         this == GetStandaloneDataSource()) << "CLD Data source misconfigured!";
+  base::AutoLock lock(m_file_lock);
+  m_cached_filepath = path;
+}
+
+base::FilePath CldDataSource::GetCldDataFilePath() {
+  DCHECK(this == GetComponentDataSource() ||
+         this == GetStandaloneDataSource()) << "CLD Data source misconfigured!";
+  base::AutoLock lock(m_file_lock);
+  return m_cached_filepath;
+}
+
+// static
+void CldDataSource::SetDefault(CldDataSource* data_source) {
+  if (g_instance == NULL) Set(data_source);
+}
+
+// static
+void CldDataSource::Set(CldDataSource* data_source) {
+  g_instance = data_source;
+}
+
+// static
+CldDataSource* CldDataSource::Get() {
+  DCHECK(g_instance != NULL) << "No CLD data source was configured!";
+  if (g_instance != NULL) return g_instance;
+  return GetStaticDataSource();
+}
+
+// static
+CldDataSource* CldDataSource::GetStaticDataSource() {
+  return &g_wrapped_static.Get();
+}
+
+// static
+CldDataSource* CldDataSource::GetStandaloneDataSource() {
+  return &g_wrapped_standalone.Get();
+}
+
+// static
+CldDataSource* CldDataSource::GetComponentDataSource() {
+  return &g_wrapped_component.Get();
+}
+
+}  // namespace translate