Remove the url parameter from blink::Platform::userAgent since it's not used anymore.

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index fe9b1af30858d0862b070be59e2352cd445cd12a..bb23b600f7eb26f18f472d5a14cc2136769f1aa5 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -323,8 +323,8 @@ public:
     // Returns a new WebSocketHandle instance.
     virtual WebSocketHandle* createWebSocketHandle() { return 0; }
 
-    // Returns the User-Agent string that should be used for the given URL.
-    virtual WebString userAgent(const WebURL&) { return WebString(); }
+    // Returns the User-Agent string.
+    virtual WebString userAgent() { return WebString(); }
 
     // A suggestion to cache this metadata in association with this URL.
     virtual void cacheMetadata(const WebURL&, double responseTime, const char* data, size_t dataSize) { }