Automatically trigger installation of high-quality speech synthesis extension.

chrome/browser/chromeos/extensions/speech_synthesis_loader.cc

+// Copyright (c) 2013 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 "chrome/browser/chromeos/extensions/speech_synthesis_loader.h"
+
+#include "base/prefs/pref_service.h"
+#include "base/values.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/extensions/external_provider_impl.h"
+#include "chrome/common/extensions/extension_constants.h"
+#include "chrome/common/pref_names.h"
+#include "components/user_prefs/pref_registry_syncable.h"
+#include "content/public/browser/browser_thread.h"
+
+using extensions::ExternalProviderImpl;
+
+namespace chromeos {
+
+SpeechSynthesisLoader::SpeechSynthesisLoader(Profile* profile)
+    : profile_(profile),
+      pref_change_registrar_(new PrefChangeRegistrar()),
+      weak_ptr_factory_(this) {
+  pref_change_registrar_->Init(profile->GetPrefs());
+  pref_change_registrar_->Add(
+      prefs::kHighQualitySpeechSynthesisLanguages,
+      base::Bind(&SpeechSynthesisLoader::StartLoading,
+                 weak_ptr_factory_.GetWeakPtr()));
+
+  lang_to_extension_id_map_["en-US"] =

[Dmitry Polukhin, 2013/12/05 18:35:32]

Nit, I suspect we will expand it in future so let's create const array of lang
to ID mapping. So move it from code to data.

[dmazzoni, 2013/12/05 23:19:47]

Done.

+      extension_misc::kHighQuality_en_US_ExtensionId;
+}
+
+SpeechSynthesisLoader::~SpeechSynthesisLoader() {
+}
+
+void SpeechSynthesisLoader::StartLoading() {
+  CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+
+  prefs_.reset(new base::DictionaryValue());
+
+  PrefService* pref_service = profile_->GetPrefs();
+  const base::ListValue* languages =
+      pref_service->GetList(prefs::kHighQualitySpeechSynthesisLanguages);

[Dmitry Polukhin, 2013/12/05 18:35:32]

Why do we need more than one language here?

[dmazzoni, 2013/12/05 23:19:47]

Suppose a French-Canadian user has their UI set to English, but they visit a lot
of French sites and read those using French TTS. I don't see any reason we
shouldn't upgrade both their English and French TTS voices.

[Dmitry Polukhin, 2013/12/05 23:29:19]

Sounds reasonable, I didn't think about this uses case. I thought about UI
language only. Thanks for the explanation!

+  for (size_t i = 0; i < languages->GetSize(); ++i) {
+    std::string lang;
+    if (!languages->GetString(i, &lang))
+      continue;
+
+    base::hash_map<std::string, std::string>::iterator iter =
+        lang_to_extension_id_map_.find(lang);
+    if (iter == lang_to_extension_id_map_.end())
+      continue;
+
+    std::string extension_id = iter->second;
+    base::DictionaryValue* extension = new base::DictionaryValue();
+    prefs_->Set(extension_id, extension);
+    extension->SetString(ExternalProviderImpl::kExternalUpdateUrl,
+                         extension_urls::GetWebstoreUpdateUrl().spec());
+    base::ListValue* supported_locales = new base::ListValue();
+    supported_locales->AppendString(g_browser_process->GetApplicationLocale());
+    extension->Set(ExternalProviderImpl::kSupportedLocales, supported_locales);
+    extension->SetBoolean(ExternalProviderImpl::kIsFromWebstore, true);
+  }
+
+  LoadFinished();
+}
+
+// static
+void SpeechSynthesisLoader::RegisterProfilePrefs(
+    user_prefs::PrefRegistrySyncable* registry) {
+  registry->RegisterListPref(prefs::kHighQualitySpeechSynthesisLanguages,
+                             user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+}
+
+}  // namespace chromeos