tools: Local tests for the speculative prefetch predictor.

chrome/browser/predictors/resource_prefetch_predictor.cc

Index: chrome/browser/predictors/resource_prefetch_predictor.cc
diff --git a/chrome/browser/predictors/resource_prefetch_predictor.cc b/chrome/browser/predictors/resource_prefetch_predictor.cc
index b6e39e5d707a295876a082e6a697016941f4fe75..a399e30d75e3a12473b599d9e78137c64b98f400 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor.cc
+++ b/chrome/browser/predictors/resource_prefetch_predictor.cc
@@ -393,8 +393,10 @@ ResourcePrefetchPredictor::~ResourcePrefetchPredictor() {}
 
 void ResourcePrefetchPredictor::StartInitialization() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  TRACE_EVENT0("browser", "ResourcePrefetchPredictor::StartInitialization");
 
-  DCHECK_EQ(NOT_INITIALIZED, initialization_state_);
+  if (initialization_state_ != NOT_INITIALIZED)
+    return;
   initialization_state_ = INITIALIZING;
 
   // Create local caches using the database as loaded.
@@ -521,7 +523,8 @@ void ResourcePrefetchPredictor::OnMainFrameRequest(
   DCHECK_EQ(INITIALIZED, initialization_state_);
 
   const GURL& main_frame_url = request.navigation_id.main_frame_url;
-  StartPrefetching(main_frame_url);
+  if (!config_.ExternalPrefetchingOnly())
+    StartPrefetching(main_frame_url);
 
   // Cleanup older navigations.
   CleanupAbandonedNavigations(request.navigation_id);