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
+translate::CldDataSource* g_instance = NULL;
+

[picksi1, 2014/09/29 15:59:08]

Definite Deja Vu now!

[Andrew Hayden (chromium.org), 2014/10/30 14:25:15]

Done.

+// Global instances for the builtin data source types
+struct WrappedNone {
+  WrappedNone() {
+    value = new translate::CldDataSource("none", false, false);
+  }

[picksi1, 2014/09/29 15:59:08]

Can we turn <Bool>,<Bool> into either 2 enums or (if it makes sense) into a
single 4-value enum, to make it clear what is going on here. e.g.
value = new translate::CldDataSource("none", FEED_THE_DOG, LIGHTS_ON);

or 

value = new translate::CldDataSource("none", ILLUMINATED_DOG_FEEDING);

Also 'value' is probably not the best name here :o).

[Andrew Hayden (chromium.org), 2014/10/30 14:25:15]

Done.

+  translate::CldDataSource* value;
+};
+base::LazyInstance<WrappedNone>::Leaky g_wrapped_none =
+    LAZY_INSTANCE_INITIALIZER;
+
+struct WrappedStatic {
+  WrappedStatic() {
+    value = new translate::CldDataSource("static", false, false);
+  }
+  translate::CldDataSource* value;
+};
+base::LazyInstance<WrappedStatic>::Leaky g_wrapped_static =
+    LAZY_INSTANCE_INITIALIZER;
+
+struct WrappedStandalone {
+  WrappedStandalone() {
+    value = new translate::CldDataSource("standalone", false, true);
+  }
+  translate::CldDataSource* value;
+};
+base::LazyInstance<WrappedStandalone>::Leaky g_wrapped_standalone =
+    LAZY_INSTANCE_INITIALIZER;
+
+struct WrappedComponent {
+  WrappedComponent() {
+    value = new translate::CldDataSource("component", true, false);
+  }
+  translate::CldDataSource* value;
+};
+base::LazyInstance<WrappedComponent>::Leaky g_wrapped_component =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace translate {
+
+CldDataSource::  CldDataSource(
+    std::string name, bool register_for_component_updates,
+    bool use_standalone_data_file) :
+        m_name(name),
+        m_register_for_component_updates(register_for_component_updates),
+        m_use_standalone_data_file(use_standalone_data_file),
+        m_cached_filepath(),
+        m_file_lock() {
+}
+
+std::string CldDataSource::GetName() {
+  return m_name;
+}
+
+bool CldDataSource::ShouldRegisterForComponentUpdates() {
+  return m_register_for_component_updates;
+}
+
+bool CldDataSource::ShouldUseStandaloneDataFile() {
+  return m_use_standalone_data_file;
+}
+
+void CldDataSource::SetCldDataFilePath(const base::FilePath& path) {
+  base::AutoLock lock(m_file_lock);
+  m_cached_filepath = path;
+}
+
+base::FilePath CldDataSource::GetCldDataFilePath() {
+  base::AutoLock lock(m_file_lock);
+  return m_cached_filepath;
+}
+
+// Static methods below.
+void CldDataSource::Set(CldDataSource* data_source, bool overwrite) {
+  if (overwrite || g_instance == NULL) {
+    g_instance = data_source;
+  }
+}
+
+CldDataSource* CldDataSource::Get() {
+  if (g_instance == NULL) {
+    // No source set. OK for test code and narrow use cases, but bad if it is
+    // a real process. Since there's no good way to differentiate these use
+    // cases at runtime, don't log a warning here.
+    return NONE();

[picksi1, 2014/09/29 15:59:08]

Can the constructor default this to NONE?

[Andrew Hayden (chromium.org), 2014/10/30 14:25:15]

Obviated.

+  }
+  return g_instance;
+}
+
+CldDataSource* CldDataSource::NONE() {
+  return g_wrapped_none.Get().value;
+}
+
+CldDataSource* CldDataSource::STATIC() {
+  return g_wrapped_static.Get().value;
+}
+
+CldDataSource* CldDataSource::STANDALONE() {
+  return g_wrapped_standalone.Get().value;
+}
+
+CldDataSource* CldDataSource::COMPONENT() {
+  return g_wrapped_component.Get().value;
+}
+
+}  // namespace translate