Ignore voice queries for Play Store app search.

Voice queries just simply close the launcher. We don't need
voice queries for Play Store app search.

Bug=736027

Change-Id: Ic34c45ad105c20598b6fc4bcb345883f55ccc012
Reviewed-on: https://chromium-review.googlesource.com/579958Reviewed-by: Yury Khmel <khmel@chromium.org>
Commit-Queue: Jiaquan He <hejq@google.com>
Cr-Commit-Position: refs/heads/master@{#488697}

chrome/browser/ui/app_list/search/arc/arc_playstore_search_provider.cc

@@ -27,7 +27,7 @@ ArcPlayStoreSearchProvider::~ArcPlayStoreSearchProvider() = default;
 
 void ArcPlayStoreSearchProvider::Start(bool is_voice_query,
                                        const base::string16& query) {
-  // TODO(crbug.com/736027): should search for voice?
+  DCHECK(!is_voice_query);
   arc::mojom::AppInstance* app_instance =
       arc::ArcServiceManager::Get()
           ? ARC_GET_INSTANCE_FOR_METHOD(