Revert CL 117933003. Re-add resource speculative prefetching code.

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 c3c6480fd5ef0932e9822791d461dec2f5339da4..5a724f250234e71d0cd7d0f3951a6e8cd0313227 100644
--- a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
+++ b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
@@ -16,6 +16,7 @@
 #include "chrome/browser/content_settings/host_content_settings_map.h"
 #include "chrome/browser/download/download_request_limiter.h"
 #include "chrome/browser/download/download_resource_throttle.h"
+#include "chrome/browser/net/resource_prefetch_predictor_observer.h"
 #include "chrome/browser/prefetch/prefetch.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/prerender/prerender_manager_factory.h"
@@ -410,6 +411,11 @@ void ChromeResourceDispatcherHostDelegate::RequestBeginning(
                                     throttles);
   }
 #endif
+
+  if (io_data->resource_prefetch_predictor_observer()) {
+    io_data->resource_prefetch_predictor_observer()->OnRequestStarted(
+        request, resource_type, info->GetChildID(), info->GetRenderFrameID());
+  }
 }
 
 void ChromeResourceDispatcherHostDelegate::DownloadStarting(
@@ -671,6 +677,9 @@ void ChromeResourceDispatcherHostDelegate::OnResponseStarted(
     }
   }
 
+  if (io_data->resource_prefetch_predictor_observer())
+    io_data->resource_prefetch_predictor_observer()->OnResponseStarted(request);
+
   // Ignores x-frame-options for the chrome signin UI.
   const std::string request_spec(
       request->first_party_for_cookies().GetOrigin().spec());
@@ -714,6 +723,11 @@ void ChromeResourceDispatcherHostDelegate::OnRequestRedirected(
   // management UI is built on top of it.
   signin::AppendMirrorRequestHeaderIfPossible(request, redirect_url, io_data);
 
+  if (io_data->resource_prefetch_predictor_observer()) {
+    io_data->resource_prefetch_predictor_observer()->OnRequestRedirected(
+        redirect_url, request);
+  }
+
 #if defined(ENABLE_CONFIGURATION_POLICY)
   if (io_data->policy_header_helper())
     io_data->policy_header_helper()->AddPolicyHeaders(redirect_url, request);