[jumbo] Specify which features namespace is intended

There are more than one namespace named features, and specifically
there are both ::printing::features and ::features. When the
compiler knows about both and is inside namespace printing,
referring to "features" will resolve to ::printing::features even
if ::features was intended.

This happens in jumbo builds in some configurations. The fix is
to clarify what features namespace is intended by using a ::
prefix. An alternative fix would be to remove ::printing::features
to ::printing::printing_features.

Change-Id: I0499ed98c3ad699e89dce8f1141c327937ba0a87
Reviewed-on: https://chromium-review.googlesource.com/1213167Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#589868}

chrome/browser/printing/printing_init.cc

@@ -23,7 +23,7 @@ void InitializePrinting(content::WebContents* web_contents) {
 #if BUILDFLAG(ENABLE_PRINT_PREVIEW)
   printing::PrintViewManager::CreateForWebContents(web_contents);
   printing::PrintPreviewMessageHandler::CreateForWebContents(web_contents);
-  if (base::FeatureList::IsEnabled(features::kNupPrinting)) {
+  if (base::FeatureList::IsEnabled(::features::kNupPrinting)) {
     printing::PdfNupConverterClient::CreateForWebContents(web_contents);
   }
 #else