Open the launcher when hotword is triggered in always-on mode.

chrome/browser/ui/app_list/app_list_view_delegate.cc

Index: chrome/browser/ui/app_list/app_list_view_delegate.cc
diff --git a/chrome/browser/ui/app_list/app_list_view_delegate.cc b/chrome/browser/ui/app_list/app_list_view_delegate.cc
index 87752b62c0edc257f4848cdbd3bc38dccbc1796a..c62666cc116babbc1ed5d7f09be697a07e711aad 100644
--- a/chrome/browser/ui/app_list/app_list_view_delegate.cc
+++ b/chrome/browser/ui/app_list/app_list_view_delegate.cc
@@ -472,8 +472,22 @@ void AppListViewDelegate::ViewClosing() {
     if (service->HotwordEnabled()) {
       HotwordService* hotword_service =
           HotwordServiceFactory::GetForProfile(profile_);
-      if (hotword_service)
+      if (hotword_service) {
         hotword_service->StopHotwordSession(this);
+
+        // If we're in always-on mode, we always want to restart hotwording
+        // after closing the launcher window. So, in always-on mode, hotwording
+        // is stopped, and then started again right away. Note that hotwording
+        // may already be stopped. The call to StopHotwordSession() above both
+        // explicitly stops hotwording, if it's running, and clears the
+        // association between the hotword service and |this|.  When starting up
+        // hotwording, pass nullptr as the client so that hotword triggers cause
+        // the launcher to open.
+        // TODO(amistry): This only works on ChromeOS since Chrome hides the
+        // launcher instead of destroying it. Make this work on Chrome.
+        if (hotword_service->IsAlwaysOnEnabled())
+          hotword_service->RequestHotwordSession(nullptr);
+      }
     }
   }
 }
@@ -519,6 +533,23 @@ void AppListViewDelegate::ToggleSpeechRecognition() {
       app_list::StartPageService::Get(profile_);
   if (service)
     service->ToggleSpeechRecognition();
+
+  // With the new hotword extension, stop the hotword session. With the launcher
+  // and NTP, this is unnecessary since the hotwording is implicitly stopped.
+  // However, for always on, hotword triggering launches the launcher which
+  // starts a session and hence starts the hotword detector. This results in the
+  // hotword detector and the speech-to-text engine running in parallel, which
+  // will conflict with each other (i.e. saying 'Ok Google' twice in a row
+  // should cause a search to happen for 'Ok Google', not two hotword triggers).
+  // To get around this, always stop the session when switching to speech
+  // recognition.
+  if (HotwordService::IsExperimentalHotwordingEnabled() &&
+      service && service->HotwordEnabled()) {
+    HotwordService* hotword_service =
+        HotwordServiceFactory::GetForProfile(profile_);
+    if (hotword_service)
+      hotword_service->StopHotwordSession(this);
+  }
 }
 
 void AppListViewDelegate::ShowForProfileByPath(
@@ -547,10 +578,12 @@ void AppListViewDelegate::OnSpeechRecognitionStateChanged(
   app_list::StartPageService* service =
       app_list::StartPageService::Get(profile_);
   // With the new hotword extension, we need to re-request hotwording after
-  // speech recognition has stopped.
+  // speech recognition has stopped. Do not request hotwording after the app
+  // list has already closed.
   if (new_state == app_list::SPEECH_RECOGNITION_READY &&
       HotwordService::IsExperimentalHotwordingEnabled() &&
-      service && service->HotwordEnabled()) {
+      service && service->HotwordEnabled() &&
+      controller_->GetAppListWindow()) {
     HotwordService* hotword_service =
         HotwordServiceFactory::GetForProfile(profile_);
     if (hotword_service) {