[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..9b5bd8410e93e6c73e46e23e8c789f6bb65298d9 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 +47,16 @@ 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) {
+      DCHECK(devices[i].is_input);
+      return true;
+    }
+  }
+#endif
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   return command_line->HasSwitch(switches::kEnableExperimentalHotwordHardware);
 }