Add callback notification for WebAudioSourceProviderImpl SetClient

This change allows the WebAudioSourceProviderImpl to register callbacks
to run when a client is set.

When the WebAudioSourceProviderImpl has a client, an audio output sink
cannot be set. In this case, the Global Media Controls (GMC) UI should
not display a device picker. This change is a part of a series of
changes for appropriately hiding this UI.


Bug: 1120620
Change-Id: I2c536f8a7234116567cff1e795ca38054e29bc62
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2369660
Commit-Queue: Noah Rose Ledesma <noahrose@google.com>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802294}

third_party/blink/public/platform/webaudiosourceprovider_impl.h

@@ -11,6 +11,7 @@
 #include <string>
 
 #include "base/callback.h"
+#include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
@@ -51,9 +52,14 @@ class BLINK_PLATFORM_EXPORT WebAudioSourceProviderImpl
                                    uint32_t frames_delayed,
                                    int sample_rate)>;
 
+  // Optionally provide a callback to be run the first time a
+  // WebAudioSourceProviderClient is attached via SetClient(). Note that the
+  // callback will be run once at most, however SetClient may be called any
+  // number of times.
   WebAudioSourceProviderImpl(
       scoped_refptr<media::SwitchableAudioRendererSink> sink,
-      media::MediaLog* media_log);
+      media::MediaLog* media_log,
+      base::OnceClosure on_set_client_callback = base::OnceClosure());
 
   // WebAudioSourceProvider implementation.
   void SetClient(WebAudioSourceProviderClient* client) override;
@@ -116,6 +122,8 @@ class BLINK_PLATFORM_EXPORT WebAudioSourceProviderImpl
 
   media::MediaLog* const media_log_;
 
+  base::OnceClosure on_set_client_callback_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<WebAudioSourceProviderImpl> weak_factory_{this};
 

third_party/blink/renderer/platform/media/webaudiosourceprovider_impl.cc

@@ -8,6 +8,7 @@
 #include <utility>
 
 #include "base/bind.h"
+#include "base/callback_forward.h"
 #include "base/check_op.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
@@ -130,13 +131,15 @@ class WebAudioSourceProviderImpl::TeeFilter
 
 WebAudioSourceProviderImpl::WebAudioSourceProviderImpl(
     scoped_refptr<media::SwitchableAudioRendererSink> sink,
-    media::MediaLog* media_log)
+    media::MediaLog* media_log,
+    base::OnceClosure on_set_client_callback /* = base::OnceClosure()*/)
     : volume_(1.0),
       state_(kStopped),
       client_(nullptr),
       sink_(std::move(sink)),
       tee_filter_(new TeeFilter()),
-      media_log_(media_log) {}
+      media_log_(media_log),
+      on_set_client_callback_(std::move(on_set_client_callback)) {}
 
 WebAudioSourceProviderImpl::~WebAudioSourceProviderImpl() = default;
 
@@ -170,6 +173,10 @@ void WebAudioSourceProviderImpl::SetClient(
     // ensures we have the same locking order when calling into |client_|.
     if (tee_filter_->initialized())
       set_format_cb_.Run();
+
+    if (on_set_client_callback_)
+      std::move(on_set_client_callback_).Run();
+
     return;
   }
 

third_party/blink/renderer/platform/media/webaudiosourceprovider_impl_test.cc

@@ -87,6 +87,8 @@ class WebAudioSourceProviderImplTest : public testing::Test,
     return true;
   }
 
+  MOCK_METHOD0(OnClientSet, void());
+
   // WebAudioSourceProviderClient implementation.
   MOCK_METHOD2(SetFormat, void(uint32_t numberOfChannels, float sampleRate));
 
@@ -114,6 +116,8 @@ class WebAudioSourceProviderImplTest : public testing::Test,
   scoped_refptr<media::MockAudioRendererSink> mock_sink_;
   scoped_refptr<WebAudioSourceProviderImpl> wasp_impl_;
 
+  base::WeakPtrFactory<WebAudioSourceProviderImplTest> weak_factory_{this};
+
   DISALLOW_COPY_AND_ASSIGN(WebAudioSourceProviderImplTest);
 };
 
@@ -320,4 +324,32 @@ TEST_F(WebAudioSourceProviderImplTest, MultipleInitializeWithSetClient) {
   ASSERT_FALSE(CompareBusses(bus1.get(), bus2.get()));
 }
 
+TEST_F(WebAudioSourceProviderImplTest, SetClientCallback) {
+  wasp_impl_ = new WebAudioSourceProviderImpl(
+      mock_sink_, &media_log_,
+      base::BindOnce(&WebAudioSourceProviderImplTest::OnClientSet,
+                     weak_factory_.GetWeakPtr()));
+  // SetClient with a nullptr client should not trigger the callback if no
+  // client is set.
+  EXPECT_CALL(*this, OnClientSet()).Times(0);
+  wasp_impl_->SetClient(nullptr);
+  ::testing::Mock::VerifyAndClearExpectations(this);
+
+  // SetClient when called with a valid client should trigger the callback once.
+  EXPECT_CALL(*this, OnClientSet()).Times(1);
+  wasp_impl_->SetClient(this);
+  base::RunLoop().RunUntilIdle();
+  ::testing::Mock::VerifyAndClearExpectations(this);
+
+  // Future calls to set client should not trigger the callback.
+  EXPECT_CALL(*this, OnClientSet()).Times(0);
+  wasp_impl_->SetClient(this);
+  base::RunLoop().RunUntilIdle();
+  wasp_impl_->SetClient(nullptr);
+  base::RunLoop().RunUntilIdle();
+  wasp_impl_->SetClient(this);
+  base::RunLoop().RunUntilIdle();
+  ::testing::Mock::VerifyAndClearExpectations(this);
+}
+
 }  // namespace blink