Simplify the Demuxer interface to get streams by type.

Before this change Demuxer's interface looked as if it could return multiple
streams for a given type, but the implementations all assume/need at most a
single stream per type.  This change should make the (soon to be written)
AdaptiveDemuxer{,Stream} less confusing.

BUG=none
TEST=trybots

Review URL: http://codereview.chromium.org/6685122

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@78908 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 17 insertions, 41 deletions

diff --git a/media/base/filters.h b/media/base/filters.h
index 654da5a..d6b962d 100644
--- a/media/base/filters.h
+++ b/media/base/filters.h
@@ -129,23 +129,13 @@ class DataSource : public Filter {
   virtual bool IsStreaming() = 0;
 };
 
-
-class Demuxer : public Filter {
- public:
-  // Returns the number of streams available
-  virtual size_t GetNumberOfStreams() = 0;
-
-  // Returns the stream for the given index, NULL otherwise
-  virtual scoped_refptr<DemuxerStream> GetStream(int stream_id) = 0;
-};
-
-
 class DemuxerStream : public base::RefCountedThreadSafe<DemuxerStream> {
  public:
   enum Type {
     UNKNOWN,
     AUDIO,
     VIDEO,
+    NUM_TYPES,  // Always keep this entry as the last one!
   };
 
   // Schedules a read.  When the |read_callback| is called, the downstream
@@ -186,6 +176,12 @@ class DemuxerStream : public base::RefCountedThreadSafe<DemuxerStream> {
   virtual ~DemuxerStream();
 };
 
+class Demuxer : public Filter {
+ public:
+  // Returns the given stream type, or NULL if that type is not present.
+  virtual scoped_refptr<DemuxerStream> GetStream(DemuxerStream::Type type) = 0;
+};
+
 
 class VideoDecoder : public Filter {
  public:
diff --git a/media/base/mock_filters.h b/media/base/mock_filters.h
index 8004190..c108c57 100644
--- a/media/base/mock_filters.h
+++ b/media/base/mock_filters.h
@@ -110,8 +110,7 @@ class MockDemuxer : public Demuxer {
   // Demuxer implementation.
   MOCK_METHOD2(Initialize, void(DataSource* data_source,
                                 FilterCallback* callback));
-  MOCK_METHOD0(GetNumberOfStreams, size_t());
-  MOCK_METHOD1(GetStream, scoped_refptr<DemuxerStream>(int stream_id));
+  MOCK_METHOD1(GetStream, scoped_refptr<DemuxerStream>(DemuxerStream::Type));
 
   // Sets the TotalBytes, BufferedBytes, & Duration values to be sent to host()
   // when set_host() is called.
diff --git a/media/base/pipeline_impl.cc b/media/base/pipeline_impl.cc
index 7c71e66..2b66661 100644
--- a/media/base/pipeline_impl.cc
+++ b/media/base/pipeline_impl.cc
@@ -1058,7 +1058,7 @@ bool PipelineImpl::InitializeAudioDecoder(
   DCHECK(IsPipelineOk());
 
   scoped_refptr<DemuxerStream> stream =
-      FindDemuxerStream(demuxer, DemuxerStream::AUDIO);
+      demuxer->GetStream(DemuxerStream::AUDIO);
 
   if (!stream)
     return false;
@@ -1088,7 +1088,7 @@ bool PipelineImpl::InitializeVideoDecoder(
   DCHECK(IsPipelineOk());
 
   scoped_refptr<DemuxerStream> stream =
-      FindDemuxerStream(demuxer, DemuxerStream::VIDEO);
+      demuxer->GetStream(DemuxerStream::VIDEO);
 
   if (!stream)
     return false;
@@ -1158,21 +1158,6 @@ bool PipelineImpl::InitializeVideoRenderer(
   return true;
 }
 
-scoped_refptr<DemuxerStream> PipelineImpl::FindDemuxerStream(
-    const scoped_refptr<Demuxer>& demuxer,
-    DemuxerStream::Type type) {
-  DCHECK(demuxer);
-
-  const int num_outputs = demuxer->GetNumberOfStreams();
-  for (int i = 0; i < num_outputs; ++i) {
-    std::string value;
-    if (demuxer->GetStream(i)->type() == type) {
-      return demuxer->GetStream(i);
-    }
-  }
-  return NULL;
-}
-
 void PipelineImpl::TearDownPipeline() {
   DCHECK_EQ(MessageLoop::current(), message_loop_);
   DCHECK_NE(kStopped, state_);
diff --git a/media/base/pipeline_impl.h b/media/base/pipeline_impl.h
index e50322b..32de091 100644
--- a/media/base/pipeline_impl.h
+++ b/media/base/pipeline_impl.h
@@ -289,12 +289,6 @@ class PipelineImpl : public Pipeline, public FilterHost {
   bool InitializeAudioRenderer(const scoped_refptr<AudioDecoder>& decoder);
   bool InitializeVideoRenderer(const scoped_refptr<VideoDecoder>& decoder);
 
-  // Returns a reference to the DemuxerStream of the requested type if it
-  // exists, NULL otherwise.
-  scoped_refptr<DemuxerStream> FindDemuxerStream(
-      const scoped_refptr<Demuxer>& demuxer,
-      DemuxerStream::Type type);
-
   // Kicks off destroying filters. Called by StopTask() and ErrorChangedTask().
   // When we start to tear down the pipeline, we will consider two cases:
   // 1. when pipeline has not been initialized, we will transit to stopping
diff --git a/media/base/pipeline_impl_unittest.cc b/media/base/pipeline_impl_unittest.cc
index c5593f3..396b69c 100644
--- a/media/base/pipeline_impl_unittest.cc
+++ b/media/base/pipeline_impl_unittest.cc
@@ -67,6 +67,12 @@ class PipelineImplTest : public ::testing::Test {
                     &CallbackHelper::OnError),
         static_cast<PipelineStatusCallback*>(NULL));
     mocks_.reset(new MockFilterCollection());
+
+    // InitializeDemuxer adds overriding expectations for expected non-NULL
+    // streams.
+    DemuxerStream* null_pointer = NULL;
+    EXPECT_CALL(*mocks_->demuxer(), GetStream(_))
+        .WillRepeatedly(Return(null_pointer));
   }
 
   virtual ~PipelineImplTest() {
@@ -90,8 +96,6 @@ class PipelineImplTest : public ::testing::Test {
                          const base::TimeDelta& duration) {
     mocks_->demuxer()->SetTotalAndBufferedBytesAndDuration(
         kTotalBytes, kBufferedBytes, duration);
-    EXPECT_CALL(*mocks_->demuxer(), GetNumberOfStreams())
-        .WillRepeatedly(Return(streams->size()));
     EXPECT_CALL(*mocks_->demuxer(), SetPlaybackRate(0.0f));
     EXPECT_CALL(*mocks_->demuxer(), Seek(base::TimeDelta(), NotNull()))
         .WillOnce(Invoke(&RunFilterCallback));
@@ -101,7 +105,7 @@ class PipelineImplTest : public ::testing::Test {
     // Configure the demuxer to return the streams.
     for (size_t i = 0; i < streams->size(); ++i) {
       scoped_refptr<DemuxerStream> stream((*streams)[i]);
-      EXPECT_CALL(*mocks_->demuxer(), GetStream(i))
+      EXPECT_CALL(*mocks_->demuxer(), GetStream(stream->type()))
           .WillRepeatedly(Return(stream));
     }
   }
@@ -353,8 +357,6 @@ TEST_F(PipelineImplTest, URLNotFound) {
 TEST_F(PipelineImplTest, NoStreams) {
   // Manually set these expectations because SetPlaybackRate() is not called if
   // we cannot fully initialize the pipeline.
-  EXPECT_CALL(*mocks_->demuxer(), GetNumberOfStreams())
-      .WillRepeatedly(Return(0));
   EXPECT_CALL(*mocks_->demuxer(), Stop(NotNull()))
       .WillOnce(Invoke(&RunStopFilterCallback));
   // TODO(acolwell,fischman): see TODO in URLNotFound above.