Refactor net predictor to use ResourceThrottles

chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc

Index: chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
diff --git a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
index 774cef9b4bb3a9d230c546f447edb5f867d9359f..cb9d2c917897771d8d29bf4d47e04739687268e8 100644
--- a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
+++ b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
@@ -31,6 +31,7 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_io_data.h"
 #include "chrome/browser/renderer_host/chrome_navigation_data.h"
+#include "chrome/browser/renderer_host/predictor_resource_throttle.h"
 #include "chrome/browser/renderer_host/safe_browsing_resource_throttle.h"
 #include "chrome/browser/renderer_host/thread_hop_resource_throttle.h"
 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
@@ -595,6 +596,11 @@ void ChromeResourceDispatcherHostDelegate::AppendStandardResourceThrottles(
 
   if (ThreadHopResourceThrottle::IsEnabled())
     throttles->push_back(new ThreadHopResourceThrottle);
+
+  if (io_data->GetPredictor()) {

[mmenke, 2016/05/23 18:50:22]

I'd suggest avoiding the knowledge that we only create this throttle if
ProfileIOData::GetPredictor returns non-NULL here.  Instead I'd suggest:

base::unique_ptr<content::ResourceThrottle> predictor_throttle =
    PredictorResourceThrottle::MaybeCreate(request, io_data);
if (predictor_throttle)
  throttles->push_back(predictor_throttle.release());

While I don't see us ever adding more complexity to the logic here, it minimizes
what this code needs to know about the throttle, and follows the pattern of most
other logic in this method (Admittedly, other code here doesn't use smart
pointers, but it should).

[Charlie Harrison, 2016/05/23 21:13:32]

SGTM. Done.

+    throttles->push_back(
+        new PredictorResourceThrottle(request, io_data->GetPredictor()));
+  }
 }
 
 bool ChromeResourceDispatcherHostDelegate::ShouldForceDownloadResource(