Fix division by zero. Test filter with empty output.

net/filter/brotli_filter_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 "base/files/file_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/path_service.h"
 #include "net/base/io_buffer.h"
 #include "net/filter/brotli_filter.h"
 #include "net/filter/mock_filter_context.h"
@@ skipping 232 matching lines @@
   char corrupt_decode_buffer[kDefaultBufferSize];
   int corrupt_decode_size = kDefaultBufferSize;
 
   int code = DecodeAllWithFilter(filter_.get(), corrupt_data, corrupt_data_len,
                                  corrupt_decode_buffer, &corrupt_decode_size);
 
   // Expect failures
   EXPECT_EQ(Filter::FILTER_ERROR, code);
 }
 
+// Decoding brotli stream with empty output data.
+TEST_F(BrotliUnitTest, DecodeEmptyData) {
+  char data[1] = {6};  // WBITS = 16, ISLAST = 1, ISLASTEMPTY = 1
+  int data_len = 1;
+
+  InitFilter();
+  char decode_buffer[kDefaultBufferSize];
+  int decode_size = kDefaultBufferSize;
+  int code = DecodeAllWithFilter(filter_.get(), data, data_len, decode_buffer,
+                                 &decode_size);
+
+  // Expect success / empty output.
+  EXPECT_EQ(Filter::FILTER_DONE, code);
+  EXPECT_EQ(0, decode_size);
+}
+
 }  // namespace net