Add support for origin trials in workers.

third_party/WebKit/Source/core/origin_trials/OriginTrialContext.h

Index: third_party/WebKit/Source/core/origin_trials/OriginTrialContext.h
diff --git a/third_party/WebKit/Source/core/origin_trials/OriginTrialContext.h b/third_party/WebKit/Source/core/origin_trials/OriginTrialContext.h
index 4e376cdba2e9784b1dc6fa53a486ad01be697594..8f13dbfab087cabe3f5d57b94b0eba37cb5de64c 100644
--- a/third_party/WebKit/Source/core/origin_trials/OriginTrialContext.h
+++ b/third_party/WebKit/Source/core/origin_trials/OriginTrialContext.h
@@ -35,10 +35,19 @@ class WebTrialTokenValidator;
 class CORE_EXPORT OriginTrialContext final : public GarbageCollectedFinalized<OriginTrialContext>, public Supplement<ExecutionContext> {
 USING_GARBAGE_COLLECTED_MIXIN(OriginTrialContext)
 public:
+    enum CreateMode {
+        CreateIfNotExists,
+        DontCreateIfNotExists
+    };
+
     explicit OriginTrialContext(ExecutionContext*);
 
     static const char* supplementName();
-    static OriginTrialContext* from(ExecutionContext*);
+
+    // Returns the OriginTrialContext for a specific ExecutionContext. If
+    // |create| is false, this returns null if no OriginTrialContext exists
+    // yet for the ExecutionContext.
+    static OriginTrialContext* from(ExecutionContext*, CreateMode = CreateIfNotExists);
 
     // Parses an Origin-Trial header as specified in
     // https://jpchase.github.io/OriginTrials/#header into individual tokens.
@@ -47,8 +56,14 @@ public:
     static std::unique_ptr<Vector<String>> parseHeaderValue(const String& headerValue);
 
     static void addTokensFromHeader(ExecutionContext*, const String& headerValue);
+    static void addTokens(ExecutionContext*, const Vector<String>* tokens);
+
+    // Returns the trial tokens that are active in a specific ExecutionContext.
+    // Returns null if no tokens were added to the ExecutionContext.
+    static std::unique_ptr<Vector<String>> getTokens(ExecutionContext*);
 
     void addToken(const String& token);
+    void addTokens(const Vector<String>& tokens);
 
     // Returns true if the feature should be considered enabled for the current
     // execution context. If non-null, the |errorMessage| parameter will be used