Fix progress reporting for multibuffers to report progress for every byte we receive.

media/blink/multibuffer_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <deque>
 #include <string>
 #include <vector>
@@ skipping 47 matching lines @@
         writers.pop_back();
         return;
       }
     }
     LOG(FATAL) << "Couldn't find myself in writers!";
   }
 
   MultiBufferBlockId Tell() const override { return pos_; }
 
   bool Available() const override { return !fifo_.empty(); }
+  int64_t AvailableBytes() const override { return 0; }
 
   scoped_refptr<DataBuffer> Read() override {
     DCHECK(Available());
     scoped_refptr<DataBuffer> ret = fifo_.front();
     fifo_.pop_front();
     ++pos_;
     return ret;
   }
 
   void SetDeferred(bool deferred) override {
@@ skipping 488 matching lines @@
     multibuffer_.CheckLRUState();
   }
   multibuffer_.CheckPresentState();
   while (!read_helpers.empty()) {
     delete read_helpers.back();
     read_helpers.pop_back();
   }
 }
 
 }  // namespace media