Bug 1370583 - Get URIClassifier service eariler. r=francois

Move the initialization of nsUrlClassifierDBService to prior of calling ShouldEnableTrackingProtection(), so the nsUrlClassifierDBService will be initialized before staring HTTP connection. If not doing so, there is a 3.x% peformance regression on android platforam.

netwerk/base/nsChannelClassifier.cpp

@@ -1200,16 +1200,16 @@ nsChannelClassifier::CheckIsTrackerWithLocalTable(nsIURIClassifierCallback* aCal
     return NS_ERROR_INVALID_ARG;
   }
 
-  if (!ShouldEnableTrackingProtection() && !ShouldEnableTrackingAnnotation()) {
-    return NS_ERROR_FAILURE;
-  }
-
   nsCOMPtr<nsIURIClassifier> uriClassifier =
     do_GetService(NS_URICLASSIFIERSERVICE_CONTRACTID, &rv);
   if (NS_FAILED(rv)) {
     return rv;
   }
 
+  if (!ShouldEnableTrackingProtection() && !ShouldEnableTrackingAnnotation()) {
+    return NS_ERROR_FAILURE;
+  }
+
   nsCOMPtr<nsIURI> uri;
   rv = mChannel->GetURI(getter_AddRefs(uri));
   if (NS_FAILED(rv) || !uri) {