[Media Session] Add AudioFocus debug API

Add a separate AudioFocusManagerDebug API to isolate the
privileged GetDebugInfoForRequest method.

BUG=875004

Change-Id: I587a73a78edf7aba3fce3f8dc722d2914098013f
Reviewed-on: https://chromium-review.googlesource.com/c/1242036
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596414}

services/media_session/audio_focus_manager.cc

@@ -223,10 +223,17 @@ void AudioFocusManager::BindToInterface(
   bindings_.AddBinding(this, std::move(request));
 }
 
+void AudioFocusManager::BindToDebugInterface(
+    mojom::AudioFocusManagerDebugRequest request) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  debug_bindings_.AddBinding(this, std::move(request));
+}
+
 void AudioFocusManager::CloseAllMojoObjects() {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
   observers_.CloseAll();
   bindings_.CloseAllBindings();
+  debug_bindings_.CloseAllBindings();
 }
 
 void AudioFocusManager::RequestAudioFocusInternal(
@@ -285,6 +292,7 @@ AudioFocusManager::AudioFocusManager() {
 AudioFocusManager::~AudioFocusManager() {
   DCHECK(observers_.empty());
   DCHECK(bindings_.empty());
+  DCHECK(debug_bindings_.empty());
 }
 
 std::unique_ptr<AudioFocusManager::StackRow>

services/media_session/audio_focus_manager.h

@@ -18,7 +18,8 @@
 
 namespace media_session {
 
-class AudioFocusManager : public mojom::AudioFocusManager {
+class AudioFocusManager : public mojom::AudioFocusManager,
+                          public mojom::AudioFocusManagerDebug {
  public:
   using RequestId = uint64_t;
 
@@ -32,13 +33,18 @@ class AudioFocusManager : public mojom::AudioFocusManager {
                          mojom::AudioFocusType type,
                          RequestAudioFocusCallback callback) override;
   void GetFocusRequests(GetFocusRequestsCallback callback) override;
+  void AddObserver(mojom::AudioFocusObserverPtr observer) override;
+
+  // mojom::AudioFocusManagerDebug.
   void GetDebugInfoForRequest(uint64_t request_id,
                               GetDebugInfoForRequestCallback callback) override;
-  void AddObserver(mojom::AudioFocusObserverPtr observer) override;
 
   // Bind to a mojom::AudioFocusManagerRequest.
   void BindToInterface(mojom::AudioFocusManagerRequest request);
 
+  // Bind to a mojom::AudioFocusManagerDebugRequest.
+  void BindToDebugInterface(mojom::AudioFocusManagerDebugRequest request);
+
   // This will close all Mojo bindings and interface pointers. This should be
   // called by the MediaSession service before it is destroyed.
   void CloseAllMojoObjects();
@@ -73,6 +79,9 @@ class AudioFocusManager : public mojom::AudioFocusManager {
   // Holds mojo bindings for the Audio Focus Manager API.
   mojo::BindingSet<mojom::AudioFocusManager> bindings_;
 
+  // Holds mojo bindings for the Audio Focus Manager Debug API.
+  mojo::BindingSet<mojom::AudioFocusManagerDebug> debug_bindings_;
+
   // Weak reference of managed observers. Observers are expected to remove
   // themselves before being destroyed.
   mojo::InterfacePtrSet<mojom::AudioFocusObserver> observers_;

services/media_session/audio_focus_manager_unittest.cc

@@ -140,6 +140,10 @@ class AudioFocusManagerTest : public testing::Test {
     // Bind |audio_focus_ptr_| to AudioFocusManager.
     connector_->BindInterface("test", mojo::MakeRequest(&audio_focus_ptr_));
 
+    // Bind |audio_focus_debug_ptr_| to AudioFocusManagerDebug.
+    connector_->BindInterface("test",
+                              mojo::MakeRequest(&audio_focus_debug_ptr_));
+
     // AudioFocusManager is a singleton so we should make sure we reset any
     // state in between tests.
     AudioFocusManager::GetInstance()->ResetForTesting();
@@ -239,8 +243,10 @@ class AudioFocusManagerTest : public testing::Test {
             },
             &result);
 
-    GetService()->GetDebugInfoForRequest(request_id, std::move(callback));
+    GetDebugService()->GetDebugInfoForRequest(request_id, std::move(callback));
+
     FlushForTesting();
+    audio_focus_debug_ptr_.FlushForTesting();
 
     return result;
   }
@@ -296,6 +302,10 @@ class AudioFocusManagerTest : public testing::Test {
     return audio_focus_ptr_.get();
   }
 
+  mojom::AudioFocusManagerDebug* GetDebugService() const {
+    return audio_focus_debug_ptr_.get();
+  }
+
   void FlushForTesting() {
     audio_focus_ptr_.FlushForTesting();
     AudioFocusManager::GetInstance()->FlushForTesting();
@@ -305,6 +315,7 @@ class AudioFocusManagerTest : public testing::Test {
   std::unique_ptr<service_manager::TestConnectorFactory> connector_factory_;
   std::unique_ptr<service_manager::Connector> connector_;
   mojom::AudioFocusManagerPtr audio_focus_ptr_;
+  mojom::AudioFocusManagerDebugPtr audio_focus_debug_ptr_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioFocusManagerTest);
 };

services/media_session/manifest.json

@@ -8,7 +8,8 @@
     "service_manager:connector": {
       "provides": {
         "app": [
-          "media_session.mojom.AudioFocusManager"
+          "media_session.mojom.AudioFocusManager",
+	  "media_session.mojom.AudioFocusManagerDebug"
         ],
         "tests": [ "*" ]
       }

services/media_session/media_session_service.cc

@@ -27,6 +27,10 @@ void MediaSessionService::OnStart() {
   registry_.AddInterface(
       base::BindRepeating(&AudioFocusManager::BindToInterface,
                           base::Unretained(AudioFocusManager::GetInstance())));
+
+  registry_.AddInterface(
+      base::BindRepeating(&AudioFocusManager::BindToDebugInterface,
+                          base::Unretained(AudioFocusManager::GetInstance())));
 }
 
 void MediaSessionService::OnBindInterface(

services/media_session/public/mojom/audio_focus.mojom

@@ -66,10 +66,13 @@ interface AudioFocusManager {
   // audio focus and their current requested type.
   GetFocusRequests() => (array<AudioFocusRequestState> requests);
 
+  // Adds observers that receive audio focus events.
+  AddObserver(AudioFocusObserver observer);
+};
+
+// Provides debug information about audio focus requests.
+interface AudioFocusManagerDebug {
   // Gets debugging information for a |MediaSession| with |request_id|.
   GetDebugInfoForRequest(uint64 request_id)
       => (MediaSessionDebugInfo debug_info);
-
-  // Adds observers that receive audio focus events.
-  AddObserver(AudioFocusObserver observer);
 };