Speculative resource prefetching - Not modify resource_type for MAIN_FRAME requests.

chrome/browser/net/resource_prefetch_predictor_observer.cc

Index: chrome/browser/net/resource_prefetch_predictor_observer.cc
diff --git a/chrome/browser/net/resource_prefetch_predictor_observer.cc b/chrome/browser/net/resource_prefetch_predictor_observer.cc
index 0de2c189a43e64bf2556898aa30599eedf51a6db..f1aad0257e3a427adc78cbd82226d1516dae4ae1 100644
--- a/chrome/browser/net/resource_prefetch_predictor_observer.cc
+++ b/chrome/browser/net/resource_prefetch_predictor_observer.cc
@@ -40,12 +40,14 @@ bool SummarizeResponse(net::URLRequest* request,
   request->GetMimeType(&summary->mime_type);
   summary->was_cached = request->was_cached();
 
-  // We want to rely on the mime_type to determine the resource type since we
-  // dont want types such as PREFETCH, SUB_RESOURCE, etc.
-  summary->resource_type =
-      ResourcePrefetchPredictor::GetResourceTypeFromMimeType(
-          summary->mime_type,
-          summary->resource_type);
+  // Use the mime_type to determine the resource type for subresources since
+  // types such as PREFETCH, SUB_RESOURCE, etc are not useful.
+  if (summary->resource_type != ResourceType::MAIN_FRAME) {
+    summary->resource_type =
+        ResourcePrefetchPredictor::GetResourceTypeFromMimeType(
+            summary->mime_type,
+            summary->resource_type);
+  }
   return true;
 }