Use std::string_view in PrefFilter.

Bug: 349741884
Change-Id: I3d63e6649e767796d39855eb2d8af5e428a3e426
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5666576
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Jan Keitel <jkeitel@google.com>
Reviewed-by: Dominic Battré <battre@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1320950}

components/prefs/json_pref_store_unittest.cc

@@ -74,7 +74,7 @@ class InterceptingPrefFilter : public PrefFilter {
   // PrefFilter implementation:
   void FilterOnLoad(PostFilterOnLoadCallback post_filter_on_load_callback,
                     base::Value::Dict pref_store_contents) override;
-  void FilterUpdate(const std::string& path) override {}
+  void FilterUpdate(std::string_view path) override {}
   OnWriteCallbackPair FilterSerializeData(
       base::Value::Dict& pref_store_contents) override {
     return std::move(on_write_callback_pair_);

components/prefs/pref_filter.h

@@ -5,7 +5,7 @@
 #ifndef COMPONENTS_PREFS_PREF_FILTER_H_
 #define COMPONENTS_PREFS_PREF_FILTER_H_
 
-#include <string>
+#include <string_view>
 #include <utility>
 
 #include "base/functional/callback_forward.h"
@@ -27,7 +27,7 @@ class COMPONENTS_PREFS_EXPORT PrefFilter {
   using PostFilterOnLoadCallback =
       base::OnceCallback<void(base::Value::Dict prefs, bool schedule_write)>;
 
-  virtual ~PrefFilter() {}
+  virtual ~PrefFilter() = default;
 
   // This method is given ownership of the |pref_store_contents| read from disk
   // before the underlying PersistentPrefStore gets to use them. It must hand
@@ -42,7 +42,7 @@ class COMPONENTS_PREFS_EXPORT PrefFilter {
 
   // Receives notification when a pref store value is changed, before Observers
   // are notified.
-  virtual void FilterUpdate(const std::string& path) = 0;
+  virtual void FilterUpdate(std::string_view path) = 0;
 
   // Receives notification when the pref store is about to serialize data
   // contained in |pref_store_contents| to a string. Modifications to

services/preferences/tracked/interceptable_pref_filter_unittest.cc

@@ -16,7 +16,7 @@ namespace {
 
 class TestInterceptablePrefFilter final : public InterceptablePrefFilter {
  public:
-  void FilterUpdate(const std::string& path) override {}
+  void FilterUpdate(std::string_view path) override {}
 
   OnWriteCallbackPair FilterSerializeData(
       base::Value::Dict& pref_store_contents) override {

services/preferences/tracked/pref_hash_filter.cc

@@ -173,7 +173,7 @@ void PrefHashFilter::Initialize(base::Value::Dict& pref_store_contents) {
 
 // Marks |path| has having changed if it is part of |tracked_paths_|. A new hash
 // will be stored for it the next time FilterSerializeData() is invoked.
-void PrefHashFilter::FilterUpdate(const std::string& path) {
+void PrefHashFilter::FilterUpdate(std::string_view path) {
   auto it = tracked_paths_.find(path);
   if (it != tracked_paths_.end())
     changed_paths_.insert(std::make_pair(path, it->second.get()));

services/preferences/tracked/pref_hash_filter.h

@@ -7,10 +7,12 @@
 
 #include <stddef.h>
 
+#include <functional>
 #include <map>
 #include <memory>
 #include <optional>
 #include <set>
+#include <string_view>
 #include <unordered_map>
 #include <vector>
 
@@ -33,11 +35,9 @@ namespace base {
 class Time;
 }  // namespace base
 
-namespace prefs {
-namespace mojom {
+namespace prefs::mojom {
 class TrackedPreferenceValidationDelegate;
 }
-}
 
 namespace user_prefs {
 class PrefRegistrySyncable;
@@ -94,7 +94,7 @@ class PrefHashFilter final : public InterceptablePrefFilter {
   void Initialize(base::Value::Dict& pref_store_contents);
 
   // PrefFilter remaining implementation.
-  void FilterUpdate(const std::string& path) override;
+  void FilterUpdate(std::string_view path) override;
   OnWriteCallbackPair FilterSerializeData(
       base::Value::Dict& pref_store_contents) override;
 
@@ -138,8 +138,14 @@ class PrefHashFilter final : public InterceptablePrefFilter {
 
   // A map of paths to TrackedPreferences; this map owns this individual
   // TrackedPreference objects.
+  struct StringViewHasher : public std::hash<std::string_view> {
+    using is_transparent = void;
+  };
   using TrackedPreferencesMap =
-      std::unordered_map<std::string, std::unique_ptr<TrackedPreference>>;
+      std::unordered_map<std::string,
+                         std::unique_ptr<TrackedPreference>,
+                         StringViewHasher,
+                         std::equal_to<>>;
 
   // A map from changed paths to their corresponding TrackedPreferences (which
   // aren't owned by this map).

services/preferences/tracked/tracked_preferences_migration_unittest.cc

@@ -7,6 +7,7 @@
 #include <memory>
 #include <set>
 #include <string>
+#include <string_view>
 #include <utility>
 #include <vector>
 
@@ -46,7 +47,7 @@ const char kPreviouslyProtectedPrefValue[] = "previously_protected_value";
 class SimpleInterceptablePrefFilter final : public InterceptablePrefFilter {
  public:
   // PrefFilter remaining implementation.
-  void FilterUpdate(const std::string& path) override { ADD_FAILURE(); }
+  void FilterUpdate(std::string_view path) override { ADD_FAILURE(); }
   OnWriteCallbackPair FilterSerializeData(
       base::Value::Dict& pref_store_contents) override {
     ADD_FAILURE();