Use the new hotword extension in the launcher when it is enabled.

chrome/browser/search/hotword_service.cc

 // Copyright 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/search/hotword_service.h"
 
+#include "base/command_line.h"
 #include "base/i18n/case_conversion.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/path_service.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/api/hotword_private/hotword_private_api.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/pending_extension_manager.h"
 #include "chrome/browser/extensions/updater/extension_updater.h"
 #include "chrome/browser/extensions/webstore_startup_installer.h"
 #include "chrome/browser/plugins/plugin_prefs.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search/hotword_service_factory.h"
 #include "chrome/common/chrome_paths.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/plugin_service.h"
 #include "content/public/common/webplugininfo.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/browser/uninstall_reason.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/one_shot_event.h"
@@ skipping 133 matching lines @@
       l10n_util::NormalizeLocale(GetCurrentLocale(profile));
   base::StringToLowerASCII(&normalized_locale);
 
   for (size_t i = 0; i < arraysize(kSupportedLocales); i++) {
     if (normalized_locale.compare(0, 2, kSupportedLocales[i]) == 0)
       return true;
   }
   return false;
 }
 
+// static
+bool HotwordService::IsExperimentalHotwordingEnabled() {
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+  return command_line->HasSwitch(switches::kEnableExperimentalHotwording);
+}
+
 HotwordService::HotwordService(Profile* profile)
     : profile_(profile),
       extension_registry_observer_(this),
       client_(NULL),
       error_message_(0),
       reinstall_pending_(false),
       weak_factory_(this) {
   extension_registry_observer_.Add(extensions::ExtensionRegistry::Get(profile));
   // This will be called during profile initialization which is a good time
   // to check the user's hotword state.
@@ skipping 254 matching lines @@
   DCHECK_EQ(pref_name, std::string(prefs::kHotwordSearchEnabled));
 
   ExtensionService* extension_service = GetExtensionService(profile_);
   if (profile_->GetPrefs()->GetBoolean(prefs::kHotwordSearchEnabled))
     EnableHotwordExtension(extension_service);
   else
     DisableHotwordExtension(extension_service);
 }
 
 void HotwordService::RequestHotwordSession(HotwordClient* client) {
-  if (!IsServiceAvailable() || client_)
+  if (!IsServiceAvailable() || (client_ && client_ != client))

[arv (Not doing code reviews), 2014/08/14 15:48:06]

This looks suspicious. Why are we exiting if the passed in client is different
from client_? Why are we assigning the client_ below? Why are we passing in
client?

[Jun Mukai, 2014/08/14 22:10:08]

IIRC there is only one client instance right now. Do we add them?  As arv points
out, the current code of client handling does not care so much about the
scenario of multiple clients.

[Anand Mistry (off Chromium), 2014/08/15 00:14:51]

I have no plans to add additional clients. My only requirement is that an
existing client be able to start another session since the current one will be
implicitly stopped when the hotword is triggered. Maybe I need a "resume" method
instead, but that seems unnecessary.

[Jun Mukai, 2014/08/15 00:30:07]

You seems not answering to our concerns.  If we can still assume single client,
why do you have to add the condition of client_ != client?

     return;
 
   client_ = client;
 
   HotwordPrivateEventService* event_service =
       BrowserContextKeyedAPIFactory<HotwordPrivateEventService>::Get(profile_);
   if (event_service)
     event_service->OnHotwordSessionRequested();
 }
 
@@ skipping 22 matching lines @@
     return false;
 
   std::string previous_locale =
       profile_->GetPrefs()->GetString(prefs::kHotwordPreviousLanguage);
   std::string locale = GetCurrentLocale(profile_);
 
   // If it's a new locale, then the old extension should be uninstalled.
   return locale != previous_locale &&
       HotwordService::DoesHotwordSupportLanguage(profile_);
 }