Add fuzzer to test Fuzz URLRequestDataJob

net/base/fuzzed_data_provider.h

Index: net/base/fuzzed_data_provider.h
diff --git a/net/base/fuzzed_data_provider.h b/net/base/fuzzed_data_provider.h
index 1e99864af11f46d17f620527c01d24276a50348f..ecdded482c92ca88216bb4ef6b6494c71ce952e7 100644
--- a/net/base/fuzzed_data_provider.h
+++ b/net/base/fuzzed_data_provider.h
@@ -42,6 +42,9 @@ class FuzzedDataProvider {
   // needed.  Value may not uniformly distributed in that range.
   uint32_t ConsumeValueInRange(uint32_t min, uint32_t max);
 
+  // Reports the remaining bytes available for fuzzed input.
+  size_t remaining_bytes() { return remaining_data_.length(); }
+
  private:
   base::StringPiece remaining_data_;