Reland of DevTools: require enabling CSS domain before running CSS.* commands.

third_party/WebKit/Source/core/inspector/InspectorCSSAgent.h

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 262 matching lines @@
 
   void CollectPlatformFontsForLayoutObject(
       LayoutObject*,
       HashCountedSet<std::pair<int, String>>*);
 
   InspectorStyleSheet* BindStyleSheet(CSSStyleSheet*);
   String UnbindStyleSheet(InspectorStyleSheet*);
   InspectorStyleSheet* InspectorStyleSheetForRule(CSSStyleRule*);
 
   InspectorStyleSheet* ViaInspectorStyleSheet(Document*);
+
+  protocol::Response AssertEnabled();
   protocol::Response AssertInspectorStyleSheetForId(const String&,
                                                     InspectorStyleSheet*&);
   protocol::Response AssertStyleSheetForId(const String&,
                                            InspectorStyleSheetBase*&);
   String DetectOrigin(CSSStyleSheet* page_style_sheet,
                       Document* owner_document);
 
   std::unique_ptr<protocol::CSS::CSSRule> BuildObjectForRule(CSSStyleRule*);
   std::unique_ptr<protocol::CSS::RuleUsage> BuildCoverageInfo(CSSStyleRule*,
                                                               bool);
@@ skipping 52 matching lines @@
   HeapHashSet<Member<Document>> invalidated_documents_;
 
   NodeToInspectorStyleSheet node_to_inspector_style_sheet_;
   NodeIdToForcedPseudoState node_id_to_forced_pseudo_state_;
 
   Member<StyleRuleUsageTracker> tracker_;
 
   Member<CSSStyleSheet> inspector_user_agent_style_sheet_;
 
   int resource_content_loader_client_id_;
+  bool was_enabled_ = false;
 
   friend class InspectorResourceContentLoaderCallback;
   friend class StyleSheetBinder;
 };
 
 }  // namespace blink
 
 #endif  // !defined(InspectorCSSAgent_h)