chromeos: Establish Mojo connection for Lacros part 2.

This CL introduces AshChromeService, which is a set of APIs that
lacros-chrome will call into.
With this CL, Mojo connection between ash-chrome and lacros-chrome
is now bidirectional.

Bug: 1094106
Test: Ran locally.
Change-Id: I169d55ad964073e8faebe069917a6a3a67ed5c84
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2254638Reviewed-by: Greg Kerr <kerrnel@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781662}

chrome/browser/chromeos/BUILD.gn

@@ -1352,6 +1352,8 @@ source_set("chromeos") {
     "kerberos/kerberos_credentials_manager_factory.h",
     "kerberos/kerberos_ticket_expiry_notification.cc",
     "kerberos/kerberos_ticket_expiry_notification.h",
+    "lacros/ash_chrome_service_impl.cc",
+    "lacros/ash_chrome_service_impl.h",
     "lacros/lacros_loader.cc",
     "lacros/lacros_loader.h",
     "lacros/lacros_manager.cc",

chrome/browser/chromeos/lacros/ash_chrome_service_impl.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 "chrome/browser/chromeos/lacros/ash_chrome_service_impl.h"
+
+#include <utility>
+
+#include "base/logging.h"
+
+namespace chromeos {
+
+AshChromeServiceImpl::AshChromeServiceImpl(
+    mojo::PendingReceiver<lacros::mojom::AshChromeService> pending_receiver)
+    : receiver_(this, std::move(pending_receiver)) {
+  // TODO(hidehiko): Remove non-critical log from here.
+  // Currently this is the signal that the connection is established.
+  LOG(WARNING) << "AshChromeService connected.";
+}
+
+AshChromeServiceImpl::~AshChromeServiceImpl() = default;
+
+}  // namespace chromeos

chrome/browser/chromeos/lacros/ash_chrome_service_impl.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 CHROME_BROWSER_CHROMEOS_LACROS_ASH_CHROME_SERVICE_IMPL_H_
+#define CHROME_BROWSER_CHROMEOS_LACROS_ASH_CHROME_SERVICE_IMPL_H_
+
+#include "chromeos/lacros/mojom/lacros.mojom.h"
+#include "mojo/public/cpp/bindings/pending_receiver.h"
+#include "mojo/public/cpp/bindings/receiver.h"
+
+namespace chromeos {
+
+// Implementation of AshChromeService. It provides a set of APIs that
+// lacros-chrome can call into.
+class AshChromeServiceImpl : public lacros::mojom::AshChromeService {
+ public:
+  explicit AshChromeServiceImpl(
+      mojo::PendingReceiver<lacros::mojom::AshChromeService> pending_receiver);
+  ~AshChromeServiceImpl() override;
+
+ private:
+  mojo::Receiver<lacros::mojom::AshChromeService> receiver_;
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_LACROS_ASH_CHROME_SERVICE_IMPL_H_

chrome/browser/chromeos/lacros/lacros_manager.cc

@@ -23,6 +23,7 @@
 #include "base/strings/string_number_conversions.h"
 #include "base/task/task_traits.h"
 #include "base/task/thread_pool.h"
+#include "chrome/browser/chromeos/lacros/ash_chrome_service_impl.h"
 #include "chrome/browser/chromeos/lacros/lacros_loader.h"
 #include "chrome/browser/chromeos/lacros/lacros_util.h"
 #include "chrome/browser/component_updater/cros_component_manager.h"
@@ -238,11 +239,20 @@ void LacrosManager::StartForeground(bool already_running) {
                                      lacros_process_.Handle(),
                                      channel.TakeLocalEndpoint());
       binder->Bind(lacros_chrome_service_.BindNewPipeAndPassReceiver());
+      lacros_chrome_service_->RequestAshChromeServiceReceiver(
+          base::BindOnce(&LacrosManager::OnAshChromeServiceReceiverReceived,
+                         weak_factory_.GetWeakPtr()));
     }
   }
   LOG(WARNING) << "Launched lacros-chrome with pid " << lacros_process_.Pid();
 }
 
+void LacrosManager::OnAshChromeServiceReceiverReceived(
+    mojo::PendingReceiver<lacros::mojom::AshChromeService> pending_receiver) {
+  ash_chrome_service_ =
+      std::make_unique<AshChromeServiceImpl>(std::move(pending_receiver));
+}
+
 void LacrosManager::OnUserSessionStarted(bool is_primary_user) {
   // Ensure this isn't called multiple times.
   session_manager::SessionManager::Get()->RemoveObserver(this);

chrome/browser/chromeos/lacros/lacros_manager.h

@@ -22,6 +22,7 @@ class CrOSComponentManager;
 
 namespace chromeos {
 
+class AshChromeServiceImpl;
 class LacrosLoader;
 
 // Manages the lifetime of lacros-chrome, and its loading status.
@@ -63,6 +64,11 @@ class LacrosManager : public session_manager::SessionManagerObserver {
   // already launched and running.
   void StartForeground(bool already_running);
 
+  // Called when PendingReceiver of AshChromeService is passed from
+  // lacros-chrome.
+  void OnAshChromeServiceReceiverReceived(
+      mojo::PendingReceiver<lacros::mojom::AshChromeService> pending_receiver);
+
   // session_manager::SessionManagerObserver:
   // Starts to load the lacros-chrome executable.
   void OnUserSessionStarted(bool is_primary_user) override;
@@ -91,6 +97,10 @@ class LacrosManager : public session_manager::SessionManagerObserver {
   // Available during lacros-chrome is running.
   mojo::Remote<lacros::mojom::LacrosChromeService> lacros_chrome_service_;
 
+  // Implementation of AshChromeService Mojo APIs.
+  // Instantiated on receiving the PendingReceiver from lacros-chrome.
+  std::unique_ptr<AshChromeServiceImpl> ash_chrome_service_;
+
   base::WeakPtrFactory<LacrosManager> weak_factory_{this};
 };
 

chromeos/lacros/browser/lacros_chrome_service_impl.cc

@@ -4,15 +4,23 @@
 
 #include "chromeos/lacros/browser/lacros_chrome_service_impl.h"
 
+#include <utility>
+
+#include "base/logging.h"
+
 namespace chromeos {
 
-LacrosChromeServiceImpl::LacrosChromeServiceImpl() {
-  // TODO(hidehiko): Remove non-error logging from here.
-  // Currently, LacrosChromeService interface is empty, so
-  // this is only way to make sure the connection is established.
-  LOG(WARNING) << "LacrosChromeService is connected";
-}
+LacrosChromeServiceImpl::LacrosChromeServiceImpl()
+    : pending_ash_chrome_service_receiver_(
+          ash_chrome_service_.BindNewPipeAndPassReceiver()) {}
 
 LacrosChromeServiceImpl::~LacrosChromeServiceImpl() = default;
 
+void LacrosChromeServiceImpl::RequestAshChromeServiceReceiver(
+    RequestAshChromeServiceReceiverCallback callback) {
+  // TODO(hidehiko): Remove non-error logging from here.
+  LOG(WARNING) << "AshChromeServiceReceiver requested.";
+  std::move(callback).Run(std::move(pending_ash_chrome_service_receiver_));
+}
+
 }  // namespace chromeos

chromeos/lacros/browser/lacros_chrome_service_impl.h

@@ -7,6 +7,7 @@
 
 #include "base/component_export.h"
 #include "chromeos/lacros/mojom/lacros.mojom.h"
+#include "mojo/public/cpp/bindings/remote.h"
 
 namespace chromeos {
 
@@ -14,8 +15,30 @@ namespace chromeos {
 class COMPONENT_EXPORT(CHROMEOS_LACROS) LacrosChromeServiceImpl
     : public lacros::mojom::LacrosChromeService {
  public:
+  // TODO(hidehiko): Add static getter of the instance.
+  // The instance of this class should be globally unique.
+
   LacrosChromeServiceImpl();
   ~LacrosChromeServiceImpl() override;
+
+  // lacros::mojom::LacrosChromeService:
+  void RequestAshChromeServiceReceiver(
+      RequestAshChromeServiceReceiverCallback callback) override;
+
+ private:
+  // Proxy to AshChromeService in ash-chrome.
+  // TODO(hidehiko): Add getter for Remote<AshChromeService>.
+  mojo::Remote<lacros::mojom::AshChromeService> ash_chrome_service_;
+
+  // Pending receiver of AshChromeService.
+  // AshChromeService is bound to mojo::Remote on construction, then
+  // when AshChromeService requests via RequestAshChromeServiceReceiver,
+  // its PendingReceiver is returned.
+  // This member holds the PendingReceiver between them. Note that even
+  // during the period, calling a method on AshChromeService via Remote
+  // should be available.
+  mojo::PendingReceiver<lacros::mojom::AshChromeService>
+      pending_ash_chrome_service_receiver_;
 };
 
 }  // namespace chromeos

chromeos/lacros/mojom/lacros.mojom

@@ -4,9 +4,19 @@
 
 module lacros.mojom;
 
+// AshChromeService defines the APIs that live in ash-chrome and are
+// accessed from lacros-chrome.
+interface AshChromeService {
+};
+
 // LacrosChromeService defines the APIs that live in lacros-chrome and
 // are accessed from ash-chrome.
 interface LacrosChromeService {
-    // TODO(hidehiko): Add API to return pending_receiver for
-    // ash-chrome interface.
+    // Returns the pending_receiver of AshChromeService.
+    // Ash-chrome is expected to call this method on initialization.
+    // Lacros-chrome may call AshChromeService APIs earlier than this
+    // invocation. In the case, the calls are queued, and processed
+    // sequentially, when ash-chrome binds the receiver to the service.
+    RequestAshChromeServiceReceiver@0() => (
+        pending_receiver<AshChromeService> receiver);
 };