Add flag to use LibAssistant Beta backend

This flag |LibAssistantBetaBackend| can be given as a command-line
flag, and will tell LibAssistant to use the BETA_DOGFOOD backend.
As a practical side-effect, this will show more useful information in
the logs, like the actual queries that were submitted.

Bug: b/157557676
Change-Id: I580461b649cdbae74f1d658329b1135d73823fdd
Tests: Launched Assistant with and without this flag.
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225260
Commit-Queue: Jeroen Dhollander <jeroendh@google.com>
Reviewed-by: Tao Wu <wutao@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773787}

chromeos/services/assistant/public/cpp/features.cc

@@ -49,6 +49,9 @@ const base::Feature kEnablePowerManager{"ChromeOSAssistantEnablePowerManager",
 const base::Feature kEnableOnDeviceAssistant{"OnDeviceAssistant",
                                              base::FEATURE_DISABLED_BY_DEFAULT};
 
+const base::Feature kEnableLibAssistantBetaBackend{
+    "LibAssistantBetaBackend", base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kEnableMediaSessionIntegration{
     "AssistantEnableMediaSessionIntegration", base::FEATURE_ENABLED_BY_DEFAULT};
 
@@ -93,6 +96,10 @@ bool IsOnDeviceAssistantEnabled() {
   return base::FeatureList::IsEnabled(kEnableOnDeviceAssistant);
 }
 
+bool IsLibAssistantBetaBackendEnabled() {
+  return base::FeatureList::IsEnabled(kEnableLibAssistantBetaBackend);
+}
+
 bool IsResponseProcessingV2Enabled() {
   return base::FeatureList::IsEnabled(kAssistantResponseProcessingV2);
 }

chromeos/services/assistant/public/cpp/features.h

@@ -75,6 +75,10 @@ extern const base::Feature kEnablePowerManager;
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC)
 extern const base::Feature kEnableOnDeviceAssistant;
 
+// Uses the LibAssistant beta backend instead of the release channel.
+COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC)
+extern const base::Feature kEnableLibAssistantBetaBackend;
+
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC) bool IsAppSupportEnabled();
 
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC) bool IsAudioEraserEnabled();
@@ -96,6 +100,9 @@ COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC) bool IsPowerManagerEnabled();
 
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC) bool IsOnDeviceAssistantEnabled();
 
+COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC)
+bool IsLibAssistantBetaBackendEnabled();
+
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC)
 bool IsResponseProcessingV2Enabled();
 

chromeos/services/assistant/utils.cc

@@ -147,6 +147,9 @@ std::string CreateLibAssistantConfig(
                          GetBaseAssistantDir().AsUTF8Unsafe());
   }
 
+  if (features::IsLibAssistantBetaBackendEnabled())
+    config.SetStringPath("internal.backend_type", "BETA_DOGFOOD");
+
   // Use http unless we're using the fake s3 server, which requires grpc.
   if (s3_server_uri_override)
     config.SetStringPath("internal.transport_type", "GRPC");