Clean up InternalSettings and ensure all settings are saved/restored

1. InternalSettingsGenerated now saves/restores all settings,
   including those don't have an automatically generated setter method
   in the class, to avoid error-prone custom save/restore in
   InternalSettings and ensure all changed settings, either changed
   by the generated setter methods or custom methods in
   InternalSettings, are saved and restored.
2. Also save/restore generic font family settings.
3. Because the page is never null (it's passed as a reference, and
   InternalSettings keep a reference to it in Member<Page>), the
   exception on null page never happens. The check and exception code
   are removed.
4. Unused and duplicate methods are removed.
5. Other simplifications and cleanups.

This addresses the recent regression about PerferCompositingToLCDText
caused by crrev.com/c/4337728. It may also fix some existing flaky
tests.

Bug: 1427271
Change-Id: Ifdc3265340a024bdfa896fd4f2d7229af9050254
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4368701
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Stefan Zager <szager@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1122468}

third_party/blink/renderer/build/scripts/templates/internal_settings_generated.cc.tmpl

@@ -10,31 +10,38 @@
 
 namespace blink {
 
-InternalSettingsGenerated::InternalSettingsGenerated(Page* page)
-    : page_(page)
-    {% for setting in settings if setting.type|to_idl_type %}
-    , {{setting.name}}_(page->GetSettings().Get{{setting.name.to_upper_camel_case()}}())
-    {% endfor %}
-{
+InternalSettingsGenerated::InternalSettingsGenerated(Page& page)
+    : InternalSettingsPageSupplementBase(page) {
+{% for setting in settings %}
+  backup_.Set{{setting.name.to_upper_camel_case()}}(
+      GetSettings().Get{{setting.name.to_upper_camel_case()}}());
+{% endfor %}
 }
 
 InternalSettingsGenerated::~InternalSettingsGenerated() {}
 
-void InternalSettingsGenerated::resetToConsistentState() {
-  {% for setting in settings if setting.type|to_idl_type %}
-  page_->GetSettings().Set{{setting.name.to_upper_camel_case()}}({{setting.name}}_);
-  {% endfor %}
+void InternalSettingsGenerated::ResetToConsistentState() {
+{% for setting in settings %}
+  GetSettings().Set{{setting.name.to_upper_camel_case()}}(
+      backup_.Get{{setting.name.to_upper_camel_case()}}());
+{% endfor %}
 }
 {% for setting in settings if setting.type|to_idl_type %}
 
-void InternalSettingsGenerated::set{{setting.name.to_upper_camel_case()}}({{setting.type|to_passing_type}} {{setting.name}}) {
-  page_->GetSettings().Set{{setting.name.to_upper_camel_case()}}({{setting.name}});
+void InternalSettingsGenerated::set{{setting.name.to_upper_camel_case()}}(
+    {{setting.type|to_passing_type}} {{setting.name}}) {
+  GetSettings().Set{{setting.name.to_upper_camel_case()}}({{setting.name}});
 }
 {% endfor %}
 
 void InternalSettingsGenerated::Trace(Visitor* visitor) const {
-  visitor->Trace(page_);
   ScriptWrappable::Trace(visitor);
+  InternalSettingsPageSupplementBase::Trace(visitor);
+}
+
+Settings& InternalSettingsGenerated::GetSettings() {
+  CHECK(GetSupplementable());
+  return GetSupplementable()->GetSettings();
 }
 
 } // namespace blink

third_party/blink/renderer/build/scripts/templates/internal_settings_generated.h.tmpl

@@ -7,6 +7,8 @@
 #define {{header_guard}}
 
 #include "base/memory/scoped_refptr.h"
+#include "third_party/blink/renderer/core/frame/settings.h"
+#include "third_party/blink/renderer/core/page/page.h"
 #include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
 #include "third_party/blink/renderer/platform/heap/garbage_collected.h"
 #include "third_party/blink/renderer/platform/heap/member.h"
@@ -15,27 +17,31 @@
 
 namespace blink {
 
-class Page;
-
-class InternalSettingsGenerated : public ScriptWrappable {
+class InternalSettingsGenerated : public ScriptWrappable,
+                                  public InternalSettingsPageSupplementBase {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
-  explicit InternalSettingsGenerated(Page*);
+  explicit InternalSettingsGenerated(Page&);
   virtual ~InternalSettingsGenerated();
-  void resetToConsistentState();
+
   {% for setting in settings if setting.type|to_idl_type %}
   void set{{setting.name.to_upper_camel_case()}}({{setting.type|to_passing_type}} {{setting.name}});
   {% endfor %}
 
   void Trace(Visitor*) const override;
 
- private:
-  Member<Page> page_;
+ protected:
+  Settings& GetSettings();
 
-  {% for setting in settings if setting.type|to_idl_type %}
-  {{setting.type}} {{setting.name}}_;
-  {% endfor %}
+  // Resets all settings to be the initial state when this is constructed.
+  // This also includes settings without an idl type (thus without an
+  // automatically generated setter method in this class), in case the settings
+  // are changed by custom methods defined in InternalSettings.
+  void ResetToConsistentState();
+
+ private:
+  Settings backup_;
 };
 
 }  // namespace blink

third_party/blink/renderer/core/frame/settings.h

@@ -56,6 +56,9 @@ class CORE_EXPORT Settings {
 
  public:
   Settings();
+
+  // Default copy and assignment are forbidden because SettingsDelegate only
+  // supports 1:1 relationship with Settings.
   Settings(const Settings&) = delete;
   Settings& operator=(const Settings&) = delete;