Tie multibuffers to URLs

media/blink/multibuffer.cc

Index: media/blink/multibuffer.cc
diff --git a/media/blink/multibuffer.cc b/media/blink/multibuffer.cc
index 41c35825f53d179b8dab721f71a4dd7baa03b25a..ffa0f18a19183ce3cef3a94f7e6d5ad5022bd0c9 100644
--- a/media/blink/multibuffer.cc
+++ b/media/blink/multibuffer.cc
@@ -161,9 +161,7 @@ void MultiBuffer::AddReader(const BlockId& pos, Reader* reader) {
   }
   if (!provider) {
     DCHECK(writer_index_.find(pos) == writer_index_.end());
-    provider = writer_index_[pos] = CreateWriter(pos);
-    provider->SetAvailableCallback(base::Bind(
-        &MultiBuffer::DataProviderEvent, base::Unretained(this), provider));
+    provider = writer_index_[pos] = CreateWriter(pos).release();
   }
   provider->SetDeferred(false);
 }
@@ -183,7 +181,7 @@ void MultiBuffer::CleanupWriters(const BlockId& pos) {
   BlockId closest_writer = ClosestPreviousEntry(writer_index_, p2);
   while (closest_writer > pos - kMaxWaitForWriterOffset) {
     DCHECK(writer_index_[closest_writer]);
-    DataProviderEvent(writer_index_[closest_writer]);
+    OnDataProviderEvent(writer_index_[closest_writer]);
     closest_writer = ClosestPreviousEntry(writer_index_, closest_writer - 1);
   }
 }
@@ -258,8 +256,12 @@ void MultiBuffer::ReleaseBlocks(const std::vector<MultiBufferBlockId>& blocks) {
       }
     }
   }
+  if (data_.empty())
+    OnEmpty();
 }
 
+void MultiBuffer::OnEmpty() {}
+
 void MultiBuffer::AddProvider(scoped_ptr<DataProvider> provider) {
   // If there is already a provider in the same location, we delete it.
   DCHECK(!provider->Available());
@@ -324,7 +326,7 @@ void MultiBuffer::Prune(size_t max_to_free) {
   lru_->Prune(max_to_free);
 }
 
-void MultiBuffer::DataProviderEvent(DataProvider* provider_tmp) {
+void MultiBuffer::OnDataProviderEvent(DataProvider* provider_tmp) {
   scoped_ptr<DataProvider> provider(RemoveProvider(provider_tmp));
   BlockId start_pos = provider->Tell();
   BlockId pos = start_pos;