Add bounds checking to StaticSocketDataProvider, to make tests more reliable

net/socket/socket_test_util.cc

Index: net/socket/socket_test_util.cc
diff --git a/net/socket/socket_test_util.cc b/net/socket/socket_test_util.cc
index 283ae352b2abccb2d6089cf61e3d5f676be07280..1ea1ec96fc22ed73a6f2d7e570ad7c2671df1444 100644
--- a/net/socket/socket_test_util.cc
+++ b/net/socket/socket_test_util.cc
@@ -284,11 +284,8 @@ int MockSSLClientSocket::Write(net::IOBuffer* buf, int buf_len,
 }
 
 MockRead StaticSocketDataProvider::GetNextRead() {
-  MockRead rv = reads_[read_index_];
-  if (reads_[read_index_].result != OK ||
-      reads_[read_index_].data_len != 0)
-    read_index_++;  // Don't advance past an EOF.
-  return rv;
+  DCHECK(!at_read_eof());
+  return reads_[read_index_++];
 }
 
 MockWriteResult StaticSocketDataProvider::OnWrite(const std::string& data) {
@@ -297,6 +294,8 @@ MockWriteResult StaticSocketDataProvider::OnWrite(const std::string& data) {
     return MockWriteResult(false, data.length());
   }
 
+  DCHECK(!at_write_eof());
+
   // Check that what we are writing matches the expectation.
   // Then give the mocked return value.
   net::MockWrite* w = &writes_[write_index_++];