components: Add out-of-line copy ctors for complex classes.

components/favicon/core/favicon_url.cc

Index: components/favicon/core/favicon_url.cc
diff --git a/components/favicon/core/favicon_url.cc b/components/favicon/core/favicon_url.cc
index 6957af6aeaade59b22de3bda387abf6eaa20c079..68bead858313c9782cd426a0fbfa2dda505e032d 100644
--- a/components/favicon/core/favicon_url.cc
+++ b/components/favicon/core/favicon_url.cc
@@ -15,6 +15,8 @@ FaviconURL::FaviconURL(const GURL& url,
     : icon_url(url), icon_type(type), icon_sizes(sizes) {
 }
 
+FaviconURL::FaviconURL(const FaviconURL& other) = default;
+
 FaviconURL::~FaviconURL() {
 }