Reduce VABC memory usage

BlockExtentWriter caches data in memory up until get gets a complete
extent. For full OTAs, extents are chopped to 2MB chunks. But for
incremental OTAs, extents can be as large as single file size. We have
observed a single extent to span >100MB disk space on pixel. This incurs
significant memory overhead depending on layout of file system image.
To reduce VABC memory usage, bound memory cache by 1MB

Test: th
Bug: 279305177
Change-Id: I75dbdd60f7e9939fc0fcabe7510fc7ff800087be
diff --git a/payload_consumer/bzip_extent_writer.h b/payload_consumer/bzip_extent_writer.h
index 38c041a..4926411 100644
--- a/payload_consumer/bzip_extent_writer.h
+++ b/payload_consumer/bzip_extent_writer.h
@@ -23,7 +23,6 @@
 
 #include <brillo/secure_blob.h>
 
-#include "update_engine/common/utils.h"
 #include "update_engine/payload_consumer/extent_writer.h"
 
 // BzipExtentWriter is a concrete ExtentWriter subclass that bzip-decompresses
@@ -46,7 +45,7 @@
 
  private:
   std::unique_ptr<ExtentWriter> next_;  // The underlying ExtentWriter.
-  bz_stream stream_;                    // the libbz2 stream
+  bz_stream stream_{};                  // the libbz2 stream
   brillo::Blob input_buffer_;
 };