Cleanup: Pass std::string as const reference if possible

url/gurl.cc

Index: url/gurl.cc
diff --git a/url/gurl.cc b/url/gurl.cc
index c22236f89e533129d935f22f5f714b2109125fea..ca46798831fcc0390c28555e805c6a6ffc5c496a 100644
--- a/url/gurl.cc
+++ b/url/gurl.cc
@@ -98,10 +98,21 @@ GURL::GURL(const char* canonical_spec,
   InitializeFromCanonicalSpec();
 }
 
-GURL::GURL(std::string canonical_spec, const url::Parsed& parsed, bool is_valid)
-    : is_valid_(is_valid),
+GURL::GURL(const std::string& canonical_spec,
+           const url::Parsed& parsed,
+           bool is_valid)
+    : spec_(canonical_spec),
+      is_valid_(is_valid),
+      parsed_(parsed) {
+  InitializeFromCanonicalSpec();
+}
+
+GURL::GURL(std::string&& canonical_spec,
+           const url::Parsed& parsed,
+           bool is_valid) noexcept
+    : spec_(std::move(canonical_spec)),
+      is_valid_(is_valid),
       parsed_(parsed) {
-  spec_.swap(canonical_spec);
   InitializeFromCanonicalSpec();
 }