prerender: Don't set the priority to net::IDLE on Android.

chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc

Index: chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
diff --git a/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc b/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
index 97cb50e63cb009c469b17f04e21d99a5de1ca62e..38daa2184b8b404ee5b0f09310c1a0da45e36058 100644
--- a/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
+++ b/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
@@ -421,6 +421,13 @@ void ChromeResourceDispatcherHostDelegate::RequestBeginning(
   if (safe_browsing_.get())
     safe_browsing_->OnResourceRequest(request);
 
+// The lowering of request priority causes issues with scheduling, since
+// content::ResourceScheduler uses it to delay and throttle requests. This is
+// disabled only on Android, as the prerenders are not likely to compete wuth

[droger, 2016/10/07 09:08:23]

s/wuth/with/

[Benoit L, 2016/10/07 09:27:35]

Done.

+// page loads there.
+// See https://crbug.com/652746 for details.
+// TODO(lizeb,droger): Remove this hack, and fix the issue on all platforms.

[droger, 2016/10/07 09:08:23]

Nit:

We're not quite sure that this is really a hack, it may be the right fix for all
platforms.
I would drop the first part of the comment and just put:

// TODO(lizeb,droger): Fix the issue on all platforms.

[Benoit L, 2016/10/07 09:27:35]

Done.

+#if !defined(OS_ANDROID)
   const ResourceRequestInfo* info = ResourceRequestInfo::ForRequest(request);
   bool is_prerendering =
       info->GetVisibilityState() == blink::WebPageVisibilityStatePrerender;
@@ -433,6 +440,7 @@ void ChromeResourceDispatcherHostDelegate::RequestBeginning(
       request->SetPriority(net::IDLE);
     }
   }
+#endif  // OS_ANDROID
 
   ProfileIOData* io_data = ProfileIOData::FromResourceContext(
       resource_context);