Port InspectorDOMStorageAgent to InspectorAgentState fields.

There's just one field for the enabled bit so this one's trivial;
I made an InnerEnable to avoid having multiple fields.

For reference the PR that introduced the new
InspectorSessionState / InspectorAgentState / Fields
was https://chromium-review.googlesource.com/c/chromium/src/+/1149201.
We're migrating things from state_ to this new mechanism,
which allows incremental updates to flow back to the browser
process.

Change-Id: I57b45ccb2595fc9167390361715cc9d795941699
Reviewed-on: https://chromium-review.googlesource.com/1159730Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Johannes Henkel <johannes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580288}

third_party/blink/renderer/modules/storage/inspector_dom_storage_agent.cc

@@ -42,13 +42,8 @@
 #include "third_party/blink/renderer/platform/weborigin/security_origin.h"
 
 namespace blink {
-
 using protocol::Response;
 
-namespace DOMStorageAgentState {
-static const char kDomStorageAgentEnabled[] = "domStorageAgentEnabled";
-};
-
 static Response ToResponse(ExceptionState& exception_state) {
   if (!exception_state.HadException())
     return Response::OK();
@@ -63,7 +58,8 @@ static Response ToResponse(ExceptionState& exception_state) {
 
 InspectorDOMStorageAgent::InspectorDOMStorageAgent(
     InspectedFrames* inspected_frames)
-    : inspected_frames_(inspected_frames), is_enabled_(false) {}
+    : inspected_frames_(inspected_frames),
+      enabled_(&agent_state_, /*default_value=*/false) {}
 
 InspectorDOMStorageAgent::~InspectorDOMStorageAgent() = default;
 
@@ -73,28 +69,28 @@ void InspectorDOMStorageAgent::Trace(blink::Visitor* visitor) {
 }
 
 void InspectorDOMStorageAgent::Restore() {
-  if (state_->booleanProperty(DOMStorageAgentState::kDomStorageAgentEnabled,
-                              false)) {
-    enable();
-  }
+  if (enabled_.Get())
+    InnerEnable();
 }
 
-Response InspectorDOMStorageAgent::enable() {
-  if (is_enabled_)
-    return Response::OK();
-  is_enabled_ = true;
-  state_->setBoolean(DOMStorageAgentState::kDomStorageAgentEnabled, true);
+void InspectorDOMStorageAgent::InnerEnable() {
   if (StorageNamespaceController* controller = StorageNamespaceController::From(
           inspected_frames_->Root()->GetPage()))
     controller->SetInspectorAgent(this);
+}
+
+Response InspectorDOMStorageAgent::enable() {
+  if (enabled_.Get())
+    return Response::OK();
+  enabled_.Set(true);
+  InnerEnable();
   return Response::OK();
 }
 
 Response InspectorDOMStorageAgent::disable() {
-  if (!is_enabled_)
+  if (!enabled_.Get())
     return Response::OK();
-  is_enabled_ = false;
-  state_->setBoolean(DOMStorageAgentState::kDomStorageAgentEnabled, false);
+  enabled_.Set(false);
   if (StorageNamespaceController* controller = StorageNamespaceController::From(
           inspected_frames_->Root()->GetPage()))
     controller->SetInspectorAgent(nullptr);

third_party/blink/renderer/modules/storage/inspector_dom_storage_agent.h

@@ -54,6 +54,7 @@ class MODULES_EXPORT InspectorDOMStorageAgent final
                                   const SecurityOrigin*);
 
  private:
+  void InnerEnable();
 
   // InspectorBaseAgent overrides.
   void Restore() override;
@@ -84,7 +85,7 @@ class MODULES_EXPORT InspectorDOMStorageAgent final
       bool is_local_storage);
 
   Member<InspectedFrames> inspected_frames_;
-  bool is_enabled_;
+  InspectorAgentState::Boolean enabled_;
 };
 
 }  // namespace blink