Support loading trial tokens from HTTP headers.

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 1b4b6772a2957519e527e8b250413092b5d323fa..7f29843ee01b8eaed2237d98908e6813707d4147 100644
--- a/third_party/WebKit/Source/core/origin_trials/OriginTrialContext.h
+++ b/third_party/WebKit/Source/core/origin_trials/OriginTrialContext.h
@@ -39,6 +39,14 @@ public:
     static const char* supplementName();
     static OriginTrialContext* from(ExecutionContext*);
 
+    // Parses an Origin-Trial header as specified in
+    // https://jpchase.github.io/OriginTrials/#header into individual tokens.
+    // Returns null if the header value was malformed and could not be parsed.
+    // If the header does not contain any tokens, this returns an empty vector.
+    static std::unique_ptr<Vector<String>> parseHeaderValue(const String& headerValue);

[Nate Chapin, 2016/04/21 22:09:10]

Is this public only for testing? If so, can we add a comment about it?

[Marijn Kruisselbrink, 2016/04/21 22:22:47]

It's also public because in a follow-up patch
(https://codereview.chromium.org/1828063002, haven't rebased it onto the latest
version of this CL yet though) the method is used from WorkerScriptLoader as
well. In earlier version of this CL I didn't have a separate parseHeaderValue
method, but since I need one anyway for that followup change, and since it makes
testing easier I figured I might as well make it a separate public method here.

So not sure if there is much point in adding a comment now, to then remove it
again fairly soon after.

[Nate Chapin, 2016/04/21 22:25:56]

Makes sense.

+
+    static void addTokensFromHeader(ExecutionContext*, const String& headerValue);
+
     void addToken(const String& token);
 
     // Returns true if the feature should be considered enabled for the current