Update zlib to 1.2.11

net/websockets/websocket_deflater.cc

Index: net/websockets/websocket_deflater.cc
diff --git a/net/websockets/websocket_deflater.cc b/net/websockets/websocket_deflater.cc
index 9144c0116dc1ab7a13084c45c2ad5534069df4ae..71e95c27fa28810f96d275c68be41a8c98e95ce8 100644
--- a/net/websockets/websocket_deflater.cc
+++ b/net/websockets/websocket_deflater.cc
@@ -31,11 +31,19 @@ bool WebSocketDeflater::Initialize(int window_bits) {
 
   DCHECK_LE(8, window_bits);
   DCHECK_GE(15, window_bits);
+
+  // Use a negative value to compress a raw deflate stream. Upgrade window_bits
+  // = 8 (a 256-byte window) to 9 (a 512-byte window) because zlib is unable to
+  // compress using a 256-byte window. This retains zlib's historical behavior
+  // of silently increasing the window size in this case. See
+  // https://crbug.com/691074.
+  window_bits = -std::max(window_bits, 9);
+
   memset(stream_.get(), 0, sizeof(*stream_));
   int result = deflateInit2(stream_.get(),
                             Z_DEFAULT_COMPRESSION,
                             Z_DEFLATED,
-                            -window_bits,  // Negative value for raw deflate
+                            window_bits,
                             8,  // default mem level
                             Z_DEFAULT_STRATEGY);
   if (result != Z_OK) {