Add a feature flag.

Bug: b/158630837
Test: manually.
Change-Id: I1a5158d54c8c4bd941c37d036c5be535175e9aa9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2261370Reviewed-by: Tao Wu <wutao@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: Meilin Wang <meilinw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781948}

ash/ambient/ambient_controller.cc

@@ -196,7 +196,8 @@ void AmbientController::OnAmbientUiVisibilityChanged(
 
       // We close the Assistant UI after ambient screen not being shown to sync
       // states to |AssistantUiController|. This will be a no-op if the
-      // Assistant UI has already been closed.
+      // |kAmbientAssistant| feature is disabled, or the Assistant UI has
+      // already been closed.
       CloseAssistantUi();
       break;
   }

ash/ambient/ui/ambient_container_view.cc

@@ -17,6 +17,7 @@
 #include "ash/public/cpp/ambient/ambient_ui_model.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/shell.h"
+#include "chromeos/services/assistant/public/cpp/features.h"
 #include "ui/aura/window.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/views/background.h"
@@ -27,6 +28,8 @@ namespace ash {
 
 namespace {
 
+using chromeos::assistant::features::IsAmbientAssistantEnabled;
+
 // Appearance.
 constexpr int kHorizontalMarginDip = 16;
 constexpr int kVerticalMarginDip = 64;
@@ -53,8 +56,11 @@ gfx::Size AmbientContainerView::CalculatePreferredSize() const {
 void AmbientContainerView::Layout() {
   // Layout child views first to have proper bounds set for children.
   LayoutPhotoView();
-  LayoutAssistantView();
   LayoutGlanceableInfoView();
+  // The assistant view may not exist if |kAmbientAssistant| feature is
+  // disabled.
+  if (ambient_assistant_container_view_)
+    LayoutAssistantView();
 
   View::Layout();
 }
@@ -65,12 +71,14 @@ void AmbientContainerView::Init() {
 
   photo_view_ = AddChildView(std::make_unique<PhotoView>(delegate_));
 
-  ambient_assistant_container_view_ =
-      AddChildView(std::make_unique<AmbientAssistantContainerView>());
-  ambient_assistant_container_view_->SetVisible(false);
-
   glanceable_info_view_ =
       AddChildView(std::make_unique<GlanceableInfoView>(delegate_));
+
+  if (IsAmbientAssistantEnabled()) {
+    ambient_assistant_container_view_ =
+        AddChildView(std::make_unique<AmbientAssistantContainerView>());
+    ambient_assistant_container_view_->SetVisible(false);
+  }
 }
 
 void AmbientContainerView::LayoutPhotoView() {

ash/assistant/assistant_ui_controller_impl.cc

@@ -28,6 +28,8 @@ namespace ash {
 
 namespace {
 
+using chromeos::assistant::features::IsAmbientAssistantEnabled;
+
 // Toast -----------------------------------------------------------------------
 
 constexpr int kToastDurationMs = 2500;
@@ -91,7 +93,7 @@ void AssistantUiControllerImpl::ShowUi(AssistantEntryPoint entry_point) {
     return;
   }
 
-  if (chromeos::features::IsAmbientModeEnabled() &&
+  if (IsAmbientAssistantEnabled() &&
       Shell::Get()->ambient_controller()->IsShown()) {
     model_.SetUiMode(AssistantUiMode::kAmbientUi);
     model_.SetVisible(entry_point);

chromeos/services/assistant/public/cpp/BUILD.gn

@@ -27,6 +27,7 @@ component("cpp") {
   ]
 
   deps = [
+    "//chromeos/constants:constants",
     "//chromeos/services/assistant/public/mojom",
     "//components/prefs",
     "//mojo/public/cpp/bindings",

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

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "chromeos/services/assistant/public/cpp/features.h"
+#include "chromeos/constants/chromeos_features.h"
 
 #include "base/feature_list.h"
 
@@ -37,6 +38,9 @@ const base::Feature kAssistantTimersV2{"AssistantTimersV2",
 const base::Feature kAssistantWaitScheduling{"AssistantWaitScheduling",
                                              base::FEATURE_ENABLED_BY_DEFAULT};
 
+const base::Feature kEnableAmbientAssistant{"EnableAmbientAssistant",
+                                            base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kEnableDspHotword{"EnableDspHotword",
                                       base::FEATURE_DISABLED_BY_DEFAULT};
 
@@ -59,6 +63,12 @@ const base::Feature kEnableMediaSessionIntegration{
 const base::Feature kDisableVoiceMatch{"DisableVoiceMatch",
                                        base::FEATURE_DISABLED_BY_DEFAULT};
 
+bool IsAmbientAssistantEnabled() {
+  return chromeos::features::IsAmbientModeEnabled() &&
+         base::FeatureList::IsEnabled(
+             assistant::features::kEnableAmbientAssistant);
+}
+
 bool IsAppSupportEnabled() {
   return base::FeatureList::IsEnabled(
       assistant::features::kAssistantAppSupport);

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

@@ -54,6 +54,10 @@ extern const base::Feature kAssistantTimersV2;
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC)
 extern const base::Feature kAssistantWaitScheduling;
 
+// Enables Assistant in Ambient Mode.
+COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC)
+extern const base::Feature kEnableAmbientAssistant;
+
 // Enables DSP for hotword detection.
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC)
 extern const base::Feature kEnableDspHotword;
@@ -79,6 +83,8 @@ extern const base::Feature kEnableOnDeviceAssistant;
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC)
 extern const base::Feature kEnableLibAssistantBetaBackend;
 
+COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC) bool IsAmbientAssistantEnabled();
+
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC) bool IsAppSupportEnabled();
 
 COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC) bool IsAudioEraserEnabled();

chromeos/services/assistant/service.cc

@@ -60,6 +60,7 @@ namespace assistant {
 
 namespace {
 
+using chromeos::assistant::features::IsAmbientAssistantEnabled;
 using CommunicationErrorType = AssistantManagerService::CommunicationErrorType;
 
 constexpr char kScopeAuthGcm[] = "https://www.googleapis.com/auth/gcm";
@@ -110,7 +111,7 @@ bool IsSignedOutMode() {
   // We will switch the Libassitsant mode to signed-out/signed-in when user
   // enters/exits the ambient mode.
   const bool entered_ambient_mode =
-      chromeos::features::IsAmbientModeEnabled() && InAmbientMode();
+      IsAmbientAssistantEnabled() && InAmbientMode();
 
   // Note that we shouldn't toggle the flag to true when exiting ambient
   // mode if we have been using fake gaia login, e.g. in the Tast test.
@@ -238,7 +239,7 @@ void Service::Init() {
 
   ash::AssistantState::Get()->AddObserver(this);
 
-  if (chromeos::features::IsAmbientModeEnabled())
+  if (IsAmbientAssistantEnabled())
     ambient_ui_model_observer_.Add(ash::AmbientUiModel::Get());
 
   DCHECK(!assistant_manager_service_);
@@ -360,6 +361,8 @@ void Service::OnStateChanged(AssistantManagerService::State new_state) {
 
 void Service::OnAmbientUiVisibilityChanged(
     ash::AmbientUiVisibility visibility) {
+  DCHECK(IsAmbientAssistantEnabled());
+
   if (IsSignedOutMode()) {
     UpdateAssistantManagerState();
   } else {
@@ -421,7 +424,7 @@ void Service::UpdateAssistantManagerState() {
     case AssistantManagerService::State::RUNNING:
       if (assistant_state->settings_enabled().value()) {
         assistant_manager_service_->SetUser(GetUserInfo());
-        if (chromeos::features::IsAmbientModeEnabled())
+        if (IsAmbientAssistantEnabled())
           assistant_manager_service_->EnableAmbientMode(InAmbientMode());
         assistant_manager_service_->EnableHotword(ShouldEnableHotword());
         assistant_manager_service_->SetArcPlayStoreEnabled(

chromeos/services/assistant/service_unittest.cc

@@ -25,6 +25,7 @@
 #include "chromeos/dbus/power/fake_power_manager_client.h"
 #include "chromeos/services/assistant/fake_assistant_manager_service_impl.h"
 #include "chromeos/services/assistant/public/cpp/assistant_prefs.h"
+#include "chromeos/services/assistant/public/cpp/features.h"
 #include "chromeos/services/assistant/test_support/fully_initialized_assistant_state.h"
 #include "chromeos/services/assistant/test_support/scoped_assistant_client.h"
 #include "chromeos/services/assistant/test_support/scoped_device_actions.h"
@@ -76,8 +77,11 @@ class AssistantServiceTest : public testing::Test {
   ~AssistantServiceTest() override = default;
 
   void SetUp() override {
-    scoped_feature_list_.InitAndEnableFeature(
-        chromeos::features::kAmbientModeFeature);
+    scoped_feature_list_.InitWithFeatures(
+        /*enabled_features=*/{chromeos::features::kAmbientModeFeature,
+                              chromeos::assistant::features::
+                                  kEnableAmbientAssistant},
+        /*disabled_features=*/{});
 
     chromeos::CrasAudioHandler::InitializeForTesting();