predictors: Add a origin for prefetch requests, remove the URL/host settings.

chrome/browser/predictors/resource_prefetch_predictor.h

Index: chrome/browser/predictors/resource_prefetch_predictor.h
diff --git a/chrome/browser/predictors/resource_prefetch_predictor.h b/chrome/browser/predictors/resource_prefetch_predictor.h
index 85b2ce270e553cf13b1ae6a119ab1cb1d00ec7b3..d4a0065d57f8ec01a19b842eac69fa269d396235 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor.h
+++ b/chrome/browser/predictors/resource_prefetch_predictor.h
@@ -151,9 +151,9 @@ class ResourcePrefetchPredictor
   // Called when the main frame of a page completes loading.
   void RecordMainFrameLoadComplete(const NavigationID& navigation_id);
 
-  // Starts prefetching if it is enabled and prefetching data exists for the
-  // |main_frame_url| either at the URL or at the host level.
-  void StartPrefetching(const GURL& main_frame_url);
+  // Starts prefetching if it is enabled for |origin| and prefetching data
+  // exists for the |main_frame_url| either at the URL or at the host level.
+  void StartPrefetching(const GURL& main_frame_url, PrefetchOrigin origin);
 
   // Stops prefetching that may be in progress corresponding to
   // |main_frame_url|.