[instrumentation] Generalize instrumentation to be used beyond the core layer

third_party/WebKit/Source/platform/loader/fetch/FetchContext.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 30 matching lines @@
 #include "platform/loader/fetch/ResourceRequest.h"
 #include "platform/weborigin/SecurityViolationReportingPolicy.h"
 #include "wtf/Forward.h"
 #include "wtf/Noncopyable.h"
 
 namespace blink {
 
 class ClientHintsPreferences;
 class KURL;
 class MHTMLArchive;
+class PlatformInstrumentationAgents;
 class ResourceError;
 class ResourceResponse;
 class ResourceTimingInfo;
 class WebTaskRunner;
 enum class WebCachePolicy;
 
 enum FetchResourceType { FetchMainResource, FetchSubresource };
 
 // The FetchContext is an interface for performing context specific processing
 // in response to events in the ResourceFetcher. The ResourceFetcher or its job
 // class, ResourceLoader, may call the methods on a FetchContext.
 //
 // Any processing that depends on components outside platform/loader/fetch/
 // should be implemented on a subclass of this interface, and then exposed to
 // the ResourceFetcher via this interface.
 class PLATFORM_EXPORT FetchContext
     : public GarbageCollectedFinalized<FetchContext> {
   WTF_MAKE_NONCOPYABLE(FetchContext);
 
  public:
   enum LogMessageType { LogErrorMessage, LogWarningMessage };
 
   static FetchContext& nullInstance();
 
   virtual ~FetchContext() {}
-  DEFINE_INLINE_VIRTUAL_TRACE() {}
+
+  DECLARE_VIRTUAL_TRACE();
 
   virtual bool isLiveContext() { return false; }
 
   virtual void addAdditionalRequestHeaders(ResourceRequest&, FetchResourceType);
   virtual CachePolicy getCachePolicy() const;
   // Returns the cache policy for the resource. ResourceRequest is not passed as
   // a const reference as a header needs to be added for doc.write blocking
   // intervention.
   virtual WebCachePolicy resourceRequestCachePolicy(
       ResourceRequest&,
@@ skipping 94 matching lines @@
 
   virtual MHTMLArchive* archive() const { return nullptr; }
 
   virtual ResourceLoadPriority modifyPriorityForExperiments(
       ResourceLoadPriority priority) {
     return priority;
   }
 
   virtual RefPtr<WebTaskRunner> loadingTaskRunner() const { return nullptr; }
 
+  PlatformInstrumentationAgents* instrumentingAgents() const {
+    return m_instrumentingAgents;
+  }
+
  protected:
-  FetchContext() {}
+  FetchContext();
+
+ private:
+  Member<PlatformInstrumentationAgents> m_instrumentingAgents;
 };
 
 }  // namespace blink
 
 #endif