[url] Reserve output buffer for various URL parsing paths

url/url_canon.h

Index: url/url_canon.h
diff --git a/url/url_canon.h b/url/url_canon.h
index c4852e490b05b0286b463ab23eca0c238eeec52a..ff66c6e3086172730eec5112cd4a8899d1a8afcc 100644
--- a/url/url_canon.h
+++ b/url/url_canon.h
@@ -117,6 +117,11 @@ class CanonOutputT {
     cur_len_ += str_len;
   }
 
+  void ReserveSizeIfNeeded(int estimated_size) {
+    if (estimated_size > buffer_len_)
+      Resize(estimated_size);
+  }
+
  protected:
   // Grows the given buffer so that it can fit at least |min_additional|
   // characters. Returns true if the buffer could be resized, false on OOM.