Hotword: Check for a speaker model before launching the opt-in flow

This is the first part of a multi-cl feature. I'll add the api functions in a followup cl to avoid having huge cls.

BUG=438525

Review URL: https://codereview.chromium.org/1020473003

Cr-Commit-Position: refs/heads/master@{#321924}

chrome/browser/search/hotword_service.cc

@@ -725,6 +725,34 @@ void HotwordService::DisableHotwordExtension(
   }
 }
 
+void HotwordService::SpeakerModelExistsComplete(bool exists) {
+  if (exists) {
+    profile_->GetPrefs()->
+        SetBoolean(prefs::kHotwordAlwaysOnSearchEnabled, true);
+  } else {
+    LaunchHotwordAudioVerificationApp(HotwordService::HOTWORD_ONLY);
+  }
+}
+
+void HotwordService::OptIntoHotwording(
+    const LaunchMode& launch_mode) {
+  // First determine if we actually need to launch the app, or can just enable
+  // the pref. If Audio History has already been enabled, and we already have
+  // a speaker model, then we don't need to launch the app at all.
+  if (launch_mode == HotwordService::HOTWORD_ONLY) {
+    HotwordPrivateEventService* event_service =
+        BrowserContextKeyedAPIFactory<HotwordPrivateEventService>::Get(
+            profile_);
+    if (event_service) {
+      // TODO(kcarattini): add this call once it's implemented in the API.
+      // event_service->SpeakerModelExists();
+      return;
+    }
+  }
+
+  LaunchHotwordAudioVerificationApp(launch_mode);
+}
+
 void HotwordService::LaunchHotwordAudioVerificationApp(
     const LaunchMode& launch_mode) {
   hotword_audio_verification_launch_mode_ = launch_mode;

chrome/browser/search/hotword_service.h

@@ -140,18 +140,26 @@ class HotwordService : public extensions::ExtensionRegistryObserver,
   // These methods are for launching, and getting and setting the launch mode of
   // the Hotword Audio Verification App.
   //
-  // TODO(kcarattini): Remove this when
-  // https://code.google.com/p/chromium/issues/detail?id=165573 is fixed,
-  // at which time we can simply launch the app in the given mode instead of
-  // having to check for it here.
+  // OptIntoHotwording first determines if the app needs to be launched, and if
+  // so, launches the app (if Audio History is on and a speaker model exists,
+  // then we don't need to launch the app).
+  //
+  // LaunchHotwordAudioVerificationApp launches the app without the above
+  // check in the specified |launch_mode|.
   enum LaunchMode {
     HOTWORD_ONLY,
     HOTWORD_AND_AUDIO_HISTORY,
     RETRAIN
   };
+  void OptIntoHotwording(const LaunchMode& launch_mode);
   void LaunchHotwordAudioVerificationApp(const LaunchMode& launch_mode);
   virtual LaunchMode GetHotwordAudioVerificationLaunchMode();
 
+  // Called when the SpeakerModelExists request is complete. Either
+  // sets the always-on hotword pref to true, or launches the Hotword
+  // Audio Verification App, depending on the value of |exists|.
+  void SpeakerModelExistsComplete(bool exists);
+
   // These methods control the speaker training communication between
   // the Hotword Audio Verification App and the Hotword Extension that
   // contains the NaCl module.

chrome/browser/ui/webui/options/browser_options_handler.cc

@@ -1871,7 +1871,7 @@ void BrowserOptionsHandler::HandleLaunchHotwordAudioVerificationApp(
   if (!hotword_service)
     return;
 
-  hotword_service->LaunchHotwordAudioVerificationApp(launch_mode);
+  hotword_service->OptIntoHotwording(launch_mode);
 }
 
 void BrowserOptionsHandler::HandleLaunchEasyUnlockSetup(