Automatically trigger installation of high-quality speech synthesis extension.

chrome/browser/extensions/external_component_loader.cc

Index: chrome/browser/extensions/external_component_loader.cc
diff --git a/chrome/browser/extensions/external_component_loader.cc b/chrome/browser/extensions/external_component_loader.cc
index ba11aa62351caf1b23a8cfefe1a7829a75f59aef..ecfc18bd44fc9a0558e92dbc6f11fa79f8c52fa4 100644
--- a/chrome/browser/extensions/external_component_loader.cc
+++ b/chrome/browser/extensions/external_component_loader.cc
@@ -5,18 +5,54 @@
 #include "chrome/browser/extensions/external_component_loader.h"
 
 #include "base/command_line.h"
+#include "base/prefs/pref_change_registrar.h"
+#include "base/prefs/pref_service.h"
 #include "base/values.h"
 #include "chrome/browser/bookmarks/enhanced_bookmarks_features.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/extensions/external_provider_impl.h"
 #include "chrome/common/chrome_switches.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"
 
 namespace extensions {
 
-ExternalComponentLoader::ExternalComponentLoader() {}
+#if defined(OS_CHROMEOS)
+namespace {
+// Table mapping language codes to the extension ids of high-quality
+// speech synthesis extensions. See the comment in StartLoading() for more.
+struct LangToExtensionId {
+  const char* lang;
+  const char* extension_id;
+};
+LangToExtensionId kLangToExtensionIdTable[] = {
+  { "en-US", extension_misc::kHighQuality_en_US_ExtensionId }
+};
+}  // anonymous namespace
+#endif  // defined(OS_CHROMEOS)
+
+ExternalComponentLoader::ExternalComponentLoader(Profile* profile)
+    : profile_(profile) {
+#if defined(OS_CHROMEOS)
+  pref_change_registrar_.reset(new PrefChangeRegistrar());
+  pref_change_registrar_->Init(profile->GetPrefs());
+  pref_change_registrar_->Add(
+      prefs::kHighQualitySpeechSynthesisLanguages,
+      base::Bind(&ExternalComponentLoader::StartLoading, AsWeakPtr()));
+
+  for (size_t i = 0; i < arraysize(kLangToExtensionIdTable); ++i) {
+    lang_to_extension_id_map_[kLangToExtensionIdTable[i].lang] =
+        kLangToExtensionIdTable[i].extension_id;
+  }
+#endif
+}
 
 ExternalComponentLoader::~ExternalComponentLoader() {}
 
 void ExternalComponentLoader::StartLoading() {
+  CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   prefs_.reset(new base::DictionaryValue());
   std::string appId = extension_misc::kInAppPaymentsSupportAppId;
   prefs_->SetString(appId + ".external_update_url",
@@ -30,7 +66,48 @@ void ExternalComponentLoader::StartLoading() {
                         extension_urls::GetWebstoreUpdateUrl().spec());
     }
   }
+
+#if defined(OS_CHROMEOS)
+  // Chrome OS comes with medium-quality speech synthesis extensions built-in.
+  // When the user speaks a certain threshold of utterances in the same
+  // session, we set a preference indicating that high quality speech is
+  // enabled for that language. Here, we check the preference and prepare
+  // the list of external extensions to be installed based on that.
+  PrefService* pref_service = profile_->GetPrefs();
+  const base::ListValue* languages =
+      pref_service->GetList(prefs::kHighQualitySpeechSynthesisLanguages);
+  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);
+  }
+#endif  // defined(OS_CHROMEOS)
+
   LoadFinished();
 }
 
+// static
+void ExternalComponentLoader::RegisterProfilePrefs(
+    user_prefs::PrefRegistrySyncable* registry) {
+#if defined(OS_CHROMEOS)
+  registry->RegisterListPref(prefs::kHighQualitySpeechSynthesisLanguages,
+                             user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+#endif
+}
+
 }  // namespace extensions