Use ByteStream in downloads system to decouple source and sink.

content/browser/download/byte_stream.h

Index: content/browser/download/byte_stream.h
diff --git a/content/browser/download/byte_stream.h b/content/browser/download/byte_stream.h
index 8265b8dd20e241885ceba8918e0bbfa745d6a4f0..f5be75aeed86f0f8f5591e860bfd6e1fb9652bc7 100644
--- a/content/browser/download/byte_stream.h
+++ b/content/browser/download/byte_stream.h
@@ -26,15 +26,15 @@ namespace content {
 // sink, which may be on different threads.  It is intended to be the
 // only connection between source and sink; they need have no
 // direct awareness of each other aside from the byte stream.  The source and
-// the sink have different interfaces to a byte stream, |ByteStreamInput|
-// and |ByteStreamOutput|.  A pair of connected interfaces is generated by
+// the sink have different interfaces to a byte stream, |ByteStreamWriter|
+// and |ByteStreamReader|.  A pair of connected interfaces is generated by
 // calling |CreateByteStream|.
 //
-// The source adds bytes to the bytestream via |ByteStreamInput::Write|
-// and the sink retrieves bytes already written via |ByteStreamOutput::Read|.
+// The source adds bytes to the bytestream via |ByteStreamWriter::Write|
+// and the sink retrieves bytes already written via |ByteStreamReader::Read|.
 //
 // When the source has no more data to add, it will call
-// |ByteStreamInput::Close| to indicate that.  Errors at the source
+// |ByteStreamWriter::Close| to indicate that.  Errors at the source
 // are indicated to the sink via a non-DOWNLOAD_INTERRUPT_REASON_NONE code.
 //
 // Normally the source is not managed after the relationship is setup;
@@ -58,9 +58,9 @@ namespace content {
 //
 // Class methods are virtual to allow mocking for tests; these classes
 // aren't intended to be base classes for other classes.
-class CONTENT_EXPORT ByteStreamInput {
+class CONTENT_EXPORT ByteStreamWriter {
 public:
-  virtual ~ByteStreamInput() = 0;
+  virtual ~ByteStreamWriter() = 0;
 
   // Always adds the data passed into the ByteStream.  Returns true
   // if more data may be added without exceeding the class limit
@@ -75,21 +75,22 @@ public:
 
   // Register a callback to be called when the stream transitions from
   // full to having space available.  The callback will always be
-  // called on the task runner associated with the ByteStreamInput.
+  // called on the task runner associated with the ByteStreamWriter.
   // This callback will only be called if a call to Write has previously
   // returned false (i.e. the ByteStream has been filled).
   // Multiple calls to this function are supported, though note that it
   // is the callers responsibility to handle races with space becoming
   // available (i.e. in the case of that race either of the before
   // or after callbacks may be called).
+  // The callback will not be called after ByteStreamWriter destruction.
   virtual void RegisterCallback(const base::Closure& source_callback) = 0;
 };
 
-class CONTENT_EXPORT ByteStreamOutput {
+class CONTENT_EXPORT ByteStreamReader {
  public:
   enum StreamState { STREAM_EMPTY, STREAM_HAS_DATA, STREAM_COMPLETE };
 
-  virtual ~ByteStreamOutput() = 0;
+  virtual ~ByteStreamReader() = 0;
 
   // Returns STREAM_EMPTY if there is no data on the ByteStream and
   // Close() has not been called, and STREAM_COMPLETE if there
@@ -109,6 +110,7 @@ class CONTENT_EXPORT ByteStreamOutput {
   // though note that it is the callers responsibility to handle races
   // with data becoming available (i.e. in the case of that race
   // either of the before or after callbacks may be called).
+  // The callback will not be called after ByteStreamReader destruction.
   virtual void RegisterCallback(const base::Closure& sink_callback) = 0;
 };
 
@@ -116,8 +118,8 @@ CONTENT_EXPORT void CreateByteStream(
     scoped_refptr<base::SequencedTaskRunner> input_task_runner,
     scoped_refptr<base::SequencedTaskRunner> output_task_runner,
     size_t buffer_size,
-    scoped_ptr<ByteStreamInput>* input,
-    scoped_ptr<ByteStreamOutput>* output);
+    scoped_ptr<ByteStreamWriter>* input,
+    scoped_ptr<ByteStreamReader>* output);
 
 }  // namespace content