Remove 'WebURLRequest::TargetType' from PrefetchHelper.

'WebURLRequest::TargetType' has been dropped in Blink in favor of
'RequestContext' and 'FrameType', matching the Fetch specification's
changes, and allowing both more granularity in various Blink-side checks
and more clarity around the thing that caused a request, and the frame
that the request affects.

This CL should have zero practical effect, as it's simply hoisting the
translation work that 'WebURLRequest::setTargetType' is already doing
up into the content layer to bring us one step closer to removing the
concept entirely.

BUG=390497

Review URL: https://codereview.chromium.org/407883005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284565 0039d316-1c4b-4281-b951-d872f2087c98

chrome/renderer/prefetch_helper.cc

@@ -33,7 +33,7 @@ bool PrefetchHelper::OnMessageReceived(
 void PrefetchHelper::OnPrefetch(const GURL& url) {
   blink::WebFrame* frame = render_frame()->GetWebFrame();
   blink::WebURLRequest request(url);
-  request.setTargetType(blink::WebURLRequest::TargetIsPrefetch);
+  request.setRequestContext(blink::WebURLRequest::RequestContextPrefetch);
   request.setPriority(blink::WebURLRequest::PriorityVeryLow);
   blink::WebURLLoaderOptions options;
   options.allowCredentials = true;