AppRTCDemo file logging.

webrtc/base/stream.h

Index: webrtc/base/stream.h
diff --git a/webrtc/base/stream.h b/webrtc/base/stream.h
index b3317663b5e3327cf4fc45ce06383aca9339ba8b..f67c704aa5155f8ed64cbc2cd2a32e4c6b376efd 100644
--- a/webrtc/base/stream.h
+++ b/webrtc/base/stream.h
@@ -418,6 +418,39 @@ class FileStream : public StreamInterface {
   DISALLOW_COPY_AND_ASSIGN(FileStream);
 };
 
+// A stream that caps the output at a certain size, dropping content from the
+// middle of the logical stream and maintaining equal parts of the start/end of
+// the logical stream.
+class CircularFileStream : public FileStream {
+ public:
+  explicit CircularFileStream(size_t max_size);
+
+  bool Open(const std::string& filename, const char* mode, int* error) override;
+  StreamResult Read(void* buffer,
+                    size_t buffer_len,
+                    size_t* read,
+                    int* error) override;
+  StreamResult Write(const void* data,
+                     size_t data_len,
+                     size_t* written,
+                     int* error) override;
+
+ private:
+  enum ReadSegment {
+    READ_MARKED,  // Read 0 .. marked_position_
+    READ_MIDDLE,  // Read position_ .. file_size
+    READ_LATEST,  // Read marked_position_ .. position_ if the buffer was
+                  // overwritten or 0 .. position_ otherwise.
+  };
+
+  size_t max_write_size_;
+  size_t position_;
+  size_t marked_position_;
+  size_t last_write_position_;
+  ReadSegment read_segment_;
+  size_t read_segment_available_;
+};
+
 ///////////////////////////////////////////////////////////////////////////////
 // MemoryStream is a simple implementation of a StreamInterface over in-memory
 // data.  Data is read and written at the current seek position.  Reads return