Let PrefRegistry::OnPrefRegistered take a std::string_view.

This CL is part of transitioning PrefRegistry to use std::string_view.
The CL contains no functional changes and incurs no extra (string)
copies in production code.

Bug: 348307659
Change-Id: I03e2546cce47f8b286efa708b4555830cabe93ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5643972
Reviewed-by: Dominic Battré <battre@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Jan Keitel <jkeitel@google.com>
Cr-Commit-Position: refs/heads/main@{#1317289}

components/prefs/pref_registry.cc

@@ -5,6 +5,8 @@
 #include "components/prefs/pref_registry.h"
 
 #include <ostream>
+#include <string>
+#include <string_view>
 #include <utility>
 
 #include "base/check_op.h"
@@ -80,5 +82,4 @@ void PrefRegistry::RegisterForeignPref(const std::string& path) {
   DCHECK(inserted);
 }
 
-void PrefRegistry::OnPrefRegistered(const std::string& path,
-                                    uint32_t flags) {}
+void PrefRegistry::OnPrefRegistered(std::string_view path, uint32_t flags) {}

components/prefs/pref_registry.h

@@ -8,6 +8,8 @@
 #include <stdint.h>
 
 #include <set>
+#include <string>
+#include <string_view>
 #include <unordered_map>
 
 #include "base/memory/ref_counted.h"
@@ -100,8 +102,7 @@ class COMPONENTS_PREFS_EXPORT PrefRegistry
                           uint32_t flags);
 
   // Allows subclasses to hook into pref registration.
-  virtual void OnPrefRegistered(const std::string& path,
-                                uint32_t flags);
+  virtual void OnPrefRegistered(std::string_view path, uint32_t flags);
 
   scoped_refptr<DefaultPrefStore> defaults_;