[Experimental Framework] Move the trial token public key out of content and into the embedder.

content/public/renderer/content_renderer_client.h

Index: content/public/renderer/content_renderer_client.h
diff --git a/content/public/renderer/content_renderer_client.h b/content/public/renderer/content_renderer_client.h
index 880550cbde9823197b05dbeed5b5ba48a77877ee..52b397f0142f020a610cb85065b94825ffcf8afe 100644
--- a/content/public/renderer/content_renderer_client.h
+++ b/content/public/renderer/content_renderer_client.h
@@ -327,6 +327,10 @@ class CONTENT_EXPORT ContentRendererClient {
   // Whether this renderer should enforce preferences related to the WebRTC
   // routing logic, i.e. allowing multiple routes and non-proxied UDP.
   virtual bool ShouldEnforceWebRTCRoutingPreferences();
+
+  // Returns the public key to be used for origin trials, or an empty string if
+  // origin trials are not enabled in this context.
+  virtual base::StringPiece GetOriginTrialPublicKey();
 };
 
 }  // namespace content