[Hotword] Set up hotwording to be externally loaded component extension. Only load if the field tri…

chrome/common/extensions/extension_constants.h

Index: chrome/common/extensions/extension_constants.h
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index 333902d479f79c5d26813e1fb626207b986a6544..d4f8271ea1b4200442b27751d01ee62966d776a8 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -109,6 +109,9 @@ namespace extension_misc {
   // The extension id of the Crosh component app for ChromeOS.
   extern const char kCroshBuiltinAppId[];
 
+  // The extension id of the hotword voice search trigger extension.
+  extern const char kHotwordExtensionId[];
+
   // The extension id of the PDF extension.
   extern const char kPdfExtensionId[];