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

chrome/browser/ui/app_list/start_page_service.cc

Index: chrome/browser/ui/app_list/start_page_service.cc
diff --git a/chrome/browser/ui/app_list/start_page_service.cc b/chrome/browser/ui/app_list/start_page_service.cc
index e57480972d17030b473ff3ffe08f4a287b51b010..f7b3b36dd5a7227bd36d21a888a5c7e950189c72 100644
--- a/chrome/browser/ui/app_list/start_page_service.cc
+++ b/chrome/browser/ui/app_list/start_page_service.cc
@@ -13,6 +13,7 @@
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/media/media_stream_infobar_delegate.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/search/hotword_service.h"
 #include "chrome/browser/search/hotword_service_factory.h"
 #include "chrome/browser/ui/app_list/recommended_apps.h"
 #include "chrome/browser/ui/app_list/start_page_observer.h"
@@ -103,6 +104,12 @@ StartPageService::StartPageService(Profile* profile)
       state_(app_list::SPEECH_RECOGNITION_OFF),
       speech_button_toggled_manually_(false),
       speech_result_obtained_(false) {
+  // If experimental hotwording is enabled, then we're always "ready".
+  // Trasitioning into the "hotword recognizing" state is handled by the hotword

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

typo

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

Done.

+  // extension.
+  if (HotwordService::IsExperimentalHotwordingEnabled())
+    state_ = app_list::SPEECH_RECOGNITION_READY;
+
   if (app_list::switches::IsExperimentalAppListEnabled())
     LoadContents();
 }
@@ -121,9 +128,15 @@ void StartPageService::AppListShown() {
   if (!contents_) {
     LoadContents();
   } else {
+    bool hotwordEnabled = HotwordEnabled();

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

variable names are in style of hotword_enabled

Also, why HotwordEnabled() doesn't use
HotwordService::IsExperimentalHotwordingEnabled() directly?

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

Done.
Because HotwordEnabled() is used in a number of other places where I don't want
it to take into account IsExperimentalHotwordingEnabled() in this way. Here, I
don't just want to know whether hotwording is enabled or not, but also whether
or not to use the hotwording built into the start page. Two orthogonal concepts.

+    // If experimental hotwording is enabled, don't enable hotwording in the
+    // start page, since the hotword extension is taking care of this.
+    if (HotwordService::IsExperimentalHotwordingEnabled())
+      hotwordEnabled = false;

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

You can simply
hotword_enabled = HotwordEnabled() &&
!HotwordService::IsExperimentalHotwordingEnabled();

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

Done.

+
     contents_->GetWebUI()->CallJavascriptFunction(
         "appList.startPage.onAppListShown",
-        base::FundamentalValue(HotwordEnabled()));
+        base::FundamentalValue(hotwordEnabled));
   }
 }
 
@@ -141,6 +154,9 @@ void StartPageService::ToggleSpeechRecognition() {
 }
 
 bool StartPageService::HotwordEnabled() {
+  if (HotwordService::IsExperimentalHotwordingEnabled())

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

needs {}

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

Done.

+    return HotwordServiceFactory::IsServiceAvailable(profile_) &&
+        profile_->GetPrefs()->GetBoolean(prefs::kHotwordSearchEnabled);
 #if defined(OS_CHROMEOS)
   return HotwordServiceFactory::IsServiceAvailable(profile_) &&
       profile_->GetPrefs()->GetBoolean(prefs::kHotwordSearchEnabled);