[Experimental Framework] Make the OriginTrialContext a member of ExecutionContext

third_party/WebKit/Source/core/dom/ExecutionContext.h

Index: third_party/WebKit/Source/core/dom/ExecutionContext.h
diff --git a/third_party/WebKit/Source/core/dom/ExecutionContext.h b/third_party/WebKit/Source/core/dom/ExecutionContext.h
index acafd94fd9d5c1930c25f1a6fbb565d7345edc58..431e3b92659f57f0c98bfe4e43cee98396e09431 100644
--- a/third_party/WebKit/Source/core/dom/ExecutionContext.h
+++ b/third_party/WebKit/Source/core/dom/ExecutionContext.h
@@ -53,6 +53,8 @@ class EventQueue;
 class EventTarget;
 class ExecutionContextTask;
 class LocalDOMWindow;
+class OriginTrials;
+class OriginTrialContext;
 class PublicURLManager;
 class SecurityOrigin;
 class ScriptCallStack;
@@ -82,6 +84,7 @@ public:
 
     virtual bool isContextThread() const { return true; }
 
+    OriginTrials* originTrials();
     SecurityOrigin* securityOrigin();
     ContentSecurityPolicy* contentSecurityPolicy();
     const KURL& url() const;
@@ -170,6 +173,9 @@ private:
     bool dispatchErrorEvent(PassRefPtrWillBeRawPtr<ErrorEvent>, AccessControlStatus);
     void runSuspendableTasks();
 
+    // Override to enable experimental features through origin trials
+    virtual OriginTrialContext* originTrialContext() { return nullptr; }
+
 #if !ENABLE(OILPAN)
     virtual void refExecutionContext() = 0;
     virtual void derefExecutionContext() = 0;
@@ -197,6 +203,9 @@ private:
     bool m_isRunSuspendableTasksScheduled;
 
     ReferrerPolicy m_referrerPolicy;
+
+    // Experimental framework policy and cache
+    OwnPtr<OriginTrials> m_originTrials;

[jbroman, 2016/03/01 23:29:21]

One thought here: consider using a supplement
(WillBeHeapSupplement<ExecutionContext>, see platform/Supplementable.h) instead
of adding a field to every execution context, especially since this is likely to
be rare (at least until developers start using the origin trials feature).
ExecutionContext is already supplementable.

I'd prefer to keep the number of feature-specific fields in ExecutionContext low
if possible.

[iclelland, 2016/03/03 21:47:01]

That's a really good idea. Thanks, done.

 };
 
 } // namespace blink