Expose Libassistant V1 classes through a singleton

This will allow us to move these classes (|AssistantManager| and
|AssistantManagerInternal|) to a new Libassistant mojom service, but
still access them from the legacy code while the transition is in
progress.

Bug: b/171748795
Test: chromeos_unittests
Cq-Include-Trybots: luci.chrome.try:linux-chromeos-chrome
Change-Id: I784c57ea1b1e89fb5ce710e031eae560e2e1cf92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2537784Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: Jeroen Dhollander <jeroendh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828225}

chromeos/services/assistant/assistant_manager_service_impl.cc

@@ -39,6 +39,7 @@
 #include "chromeos/services/assistant/public/cpp/assistant_client.h"
 #include "chromeos/services/assistant/public/cpp/device_actions.h"
 #include "chromeos/services/assistant/public/cpp/features.h"
+#include "chromeos/services/assistant/public/cpp/libassistant_v1_api.h"
 #include "chromeos/services/assistant/public/shared/utils.h"
 #include "chromeos/services/assistant/service_context.h"
 #include "chromeos/services/assistant/utils.h"
@@ -1380,16 +1381,14 @@ CrosDisplayConnection* AssistantManagerServiceImpl::display_connection() {
 
 assistant_client::AssistantManager*
 AssistantManagerServiceImpl::assistant_manager() {
-  if (!IsServiceStarted())
-    return nullptr;
-  return service_controller().assistant_manager();
+  auto* api = LibassistantV1Api::Get();
+  return api ? api->assistant_manager() : nullptr;
 }
 
 assistant_client::AssistantManagerInternal*
 AssistantManagerServiceImpl::assistant_manager_internal() {
-  if (!IsServiceStarted())
-    return nullptr;
-  return service_controller().assistant_manager_internal();
+  auto* api = LibassistantV1Api::Get();
+  return api ? api->assistant_manager_internal() : nullptr;
 }
 
 ServiceController& AssistantManagerServiceImpl::service_controller() {

chromeos/services/assistant/proxy/service_controller.cc

@@ -10,6 +10,7 @@
 #include "chromeos/constants/chromeos_features.h"
 #include "chromeos/services/assistant/assistant_manager_service_delegate.h"
 #include "chromeos/services/assistant/public/cpp/features.h"
+#include "chromeos/services/assistant/public/cpp/libassistant_v1_api.h"
 #include "libassistant/shared/internal_api/assistant_manager_internal.h"
 #include "libassistant/shared/internal_api/fuchsia_api_helper.h"
 
@@ -223,6 +224,7 @@ void ServiceController::Stop() {
   display_connection_ = nullptr;
   assistant_manager_ = nullptr;
   assistant_manager_internal_ = nullptr;
+  libassistant_v1_api_ = nullptr;
 }
 
 void ServiceController::UpdateInternalOptions(const std::string& locale,
@@ -255,6 +257,10 @@ void ServiceController::OnAssistantCreated(
   assistant_manager_ = std::move(assistant_manager);
   assistant_manager_internal_ = assistant_manager_internal;
 
+  // Expose the Libassistant V1 API to the legacy code.
+  libassistant_v1_api_ = std::make_unique<LibassistantV1Api>(
+      assistant_manager_.get(), assistant_manager_internal_);
+
   std::move(done_callback).Run();
 }
 

chromeos/services/assistant/proxy/service_controller.h

@@ -36,6 +36,7 @@ namespace assistant {
 class AssistantEventObserver;
 class AssistantManagerServiceDelegate;
 class CrosDisplayConnection;
+class LibassistantV1Api;
 
 class ServiceController {
  public:
@@ -58,18 +59,6 @@ class ServiceController {
     return display_connection_.get();
   }
 
-  // Can not be invoked before Start() has finished.
-  assistant_client::AssistantManager* assistant_manager() {
-    DCHECK(IsStarted());
-    return assistant_manager_.get();
-  }
-
-  // Can not be invoked before Start() has finished.
-  assistant_client::AssistantManagerInternal* assistant_manager_internal() {
-    DCHECK(IsStarted());
-    return assistant_manager_internal_;
-  }
-
   // Initialize the |AssistantManager| and all related objects by creating
   // them on a background task and by calling their Start() methods. Will signal
   // the objects exist and can be accessed by calling the |done_callback|.
@@ -120,6 +109,18 @@ class ServiceController {
     kStopped,
   };
 
+  // Can not be invoked before Start() has finished.
+  assistant_client::AssistantManager* assistant_manager() {
+    DCHECK(IsStarted());
+    return assistant_manager_.get();
+  }
+
+  // Can not be invoked before Start() has finished.
+  assistant_client::AssistantManagerInternal* assistant_manager_internal() {
+    DCHECK(IsStarted());
+    return assistant_manager_internal_;
+  }
+
   void OnAssistantCreated(
       base::OnceClosure done_callback,
       std::unique_ptr<CrosDisplayConnection> display_connection,
@@ -140,6 +141,8 @@ class ServiceController {
   assistant_client::AssistantManagerInternal* assistant_manager_internal_ =
       nullptr;
 
+  std::unique_ptr<LibassistantV1Api> libassistant_v1_api_;
+
   base::WeakPtrFactory<ServiceController> weak_factory_;
 };
 }  // namespace assistant

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

@@ -24,6 +24,8 @@ component("cpp") {
     "device_actions.h",
     "features.cc",
     "features.h",
+    "libassistant_v1_api.cc",
+    "libassistant_v1_api.h",
   ]
 
   public_deps = [

chromeos/services/assistant/public/cpp/libassistant_v1_api.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chromeos/services/assistant/public/cpp/libassistant_v1_api.h"
+
+#include "base/check.h"
+#include "base/check_op.h"
+
+namespace chromeos {
+namespace assistant {
+
+// static
+LibassistantV1Api* LibassistantV1Api::instance_ = nullptr;
+
+LibassistantV1Api::LibassistantV1Api(
+    assistant_client::AssistantManager* assistant_manager,
+    assistant_client::AssistantManagerInternal* assistant_manager_internal)
+    : assistant_manager_(assistant_manager),
+      assistant_manager_internal_(assistant_manager_internal) {
+  DCHECK(!instance_);
+  instance_ = this;
+}
+
+LibassistantV1Api::~LibassistantV1Api() {
+  instance_ = nullptr;
+}
+
+}  // namespace assistant
+}  // namespace chromeos

chromeos/services/assistant/public/cpp/libassistant_v1_api.h

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMEOS_SERVICES_ASSISTANT_PUBLIC_CPP_LIBASSISTANT_V1_API_H_
+#define CHROMEOS_SERVICES_ASSISTANT_PUBLIC_CPP_LIBASSISTANT_V1_API_H_
+
+#include "base/component_export.h"
+
+namespace assistant_client {
+class AssistantManager;
+class AssistantManagerInternal;
+}  // namespace assistant_client
+
+namespace chromeos {
+namespace assistant {
+
+// Singleton access to the Libassistant V1 objects.
+// Only a single instance of this class may exist at any given time.
+// TODO(b/171748795): Remove once all Libassistant access has been moved in the
+// //chromeos/services/libassistant service.
+class COMPONENT_EXPORT(ASSISTANT_SERVICE_PUBLIC) LibassistantV1Api {
+ public:
+  LibassistantV1Api(
+      assistant_client::AssistantManager* assistant_manager,
+      assistant_client::AssistantManagerInternal* assistant_manager_internal);
+  ~LibassistantV1Api();
+
+  // Return the registered instance. Can be null if no instance was registered.
+  static LibassistantV1Api* Get() { return instance_; }
+
+  assistant_client::AssistantManager* assistant_manager() {
+    return assistant_manager_;
+  }
+
+  assistant_client::AssistantManagerInternal* assistant_manager_internal() {
+    return assistant_manager_internal_;
+  }
+
+ private:
+  static LibassistantV1Api* instance_;
+  assistant_client::AssistantManager* const assistant_manager_;
+  assistant_client::AssistantManagerInternal* const assistant_manager_internal_;
+};
+
+}  // namespace assistant
+}  // namespace chromeos
+
+#endif  // CHROMEOS_SERVICES_ASSISTANT_PUBLIC_CPP_LIBASSISTANT_V1_API_H_