[Hotword] Implement IsHotwordHardwareAvailable() using device types.

chrome/browser/search/hotword_service_factory.cc

Index: chrome/browser/search/hotword_service_factory.cc
diff --git a/chrome/browser/search/hotword_service_factory.cc b/chrome/browser/search/hotword_service_factory.cc
index ed2dabc7763b48137343fcc3cf7cbbe6febf79de..eca590785db9ee8caab347c54c659a82693f72de 100644
--- a/chrome/browser/search/hotword_service_factory.cc
+++ b/chrome/browser/search/hotword_service_factory.cc
@@ -15,6 +15,10 @@
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 
+#if defined(OS_CHROMEOS)
+#include "chromeos/audio/cras_audio_handler.h"
+#endif
+
 using content::BrowserContext;
 using content::BrowserThread;
 
@@ -43,10 +47,14 @@ bool HotwordServiceFactory::IsHotwordAllowed(BrowserContext* context) {
 
 // static
 bool HotwordServiceFactory::IsHotwordHardwareAvailable() {
-  // TODO(rlp, dgreid): return has_hotword_hardware()
-  // Fill in once the hardware has the correct interface implemented.
-  // In the meantime, this function can be used to get other parts moving
-  // based on a flag.
+#if defined(OS_CHROMEOS)
+  chromeos::AudioDeviceList devices;
+  chromeos::CrasAudioHandler::Get()->GetAudioDevices(&devices);
+  for (size_t i = 0; i < devices.size(); ++i) {
+    if (devices[i].type == chromeos::AUDIO_TYPE_AOKR)

[jennyz, 2014/12/13 00:05:01]

By the way, do you know if this device is an input or output device? 

[dgreid, 2014/12/13 00:06:11]

always input.

[jennyz, 2014/12/13 00:08:14]

How about
DCHECK(devices[i].is_input)?

[jennyz, 2014/12/13 00:17:36]

I think it makes more sense to DCHECK it is input device here.

[rpetterson, 2014/12/13 00:56:27]

Ah, got it. I got the lines confused before. Done.

+      return true;
+  }
+#endif
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   return command_line->HasSwitch(switches::kEnableExperimentalHotwordHardware);
 }