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

components/translate/content/renderer/renderer_cld_data_provider.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 "base/lazy_instance.h"
+#include "components/translate/content/renderer/renderer_cld_data_provider.h"
+
+namespace {
+
+// Our global default instance, alive for the entire lifetime of the process.
+translate::RendererCldDataProvider* g_instance = NULL;
+
+// The default factory, which produces no-op instances of
+// RendererCldDataProvider suitable for use when CLD data is statically-linked.
+base::LazyInstance<translate::RendererCldDataProvider>::Leaky
+g_wrapped_default = LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+
+namespace translate {
+
+bool RendererCldDataProvider::IsCldDataAvailable() {
+  return true;
+}
+
+bool RendererCldDataProvider::OnMessageReceived(const IPC::Message& message) {
+  return false;  // Message not handled
+}
+
+void RendererCldDataProvider::SetCldAvailableCallback
+(base::Callback<void(void)> callback) {
+  callback.Run();
+}
+
+// static
+void RendererCldDataProvider::SetDefault(
+    RendererCldDataProvider* instance) {
+  if (!IsInitialized()) Set(instance);
+}
+
+// static
+void RendererCldDataProvider::Set(
+    RendererCldDataProvider* instance) {
+  g_instance = instance;
+}
+
+// static
+bool RendererCldDataProvider::IsInitialized() {
+  return g_instance != NULL;
+}
+
+// static
+RendererCldDataProvider* RendererCldDataProvider::Get() {
+  if (IsInitialized()) return g_instance;
+  return &g_wrapped_default.Get();
+}
+
+}  // namespace translate