Use net's response header parser for parsing multipart headers.

net/http/http_util.cc

Index: net/http/http_util.cc
diff --git a/net/http/http_util.cc b/net/http/http_util.cc
index baa2eff1043a34926c328be9eeadf15d08cbf3cd..5d314d12f688d3aef71f2c2686e83962d7666825 100644
--- a/net/http/http_util.cc
+++ b/net/http/http_util.cc
@@ -542,9 +542,19 @@ int HttpUtil::LocateStartOfStatusLine(const char* buf, int buf_len) {
   return -1;  // Not found
 }
 
-int HttpUtil::LocateEndOfHeaders(const char* buf, int buf_len, int i) {
-  bool was_lf = false;
+static int LocateEndOfHeadersHelper(const char* buf,
+                                    int buf_len,
+                                    int i,
+                                    bool accept_empty_header_list) {
   char last_c = '\0';
+  bool was_lf = false;
+  if (accept_empty_header_list) {
+    // Normally two line breaks signal the end of a header list. An empty header
+    // list ends with a single line break at the start of the buffer.
+    last_c = '\n';
+    was_lf = true;
+  }
+
   for (; i < buf_len; ++i) {
     char c = buf[i];
     if (c == '\n') {
@@ -559,6 +569,16 @@ int HttpUtil::LocateEndOfHeaders(const char* buf, int buf_len, int i) {
   return -1;
 }
 
+int HttpUtil::LocateEndOfAdditionalHeaders(const char* buf,
+                                           int buf_len,
+                                           int i) {
+  return LocateEndOfHeadersHelper(buf, buf_len, i, true);
+}
+
+int HttpUtil::LocateEndOfHeaders(const char* buf, int buf_len, int i) {
+  return LocateEndOfHeadersHelper(buf, buf_len, i, false);
+}
+
 // In order for a line to be continuable, it must specify a
 // non-blank header-name. Line continuations are specifically for
 // header values -- do not allow headers names to span lines.