Fix NTP thumbnail generation

chrome/browser/thumbnails/thumbnail_tab_helper.cc

Index: chrome/browser/thumbnails/thumbnail_tab_helper.cc
diff --git a/chrome/browser/thumbnails/thumbnail_tab_helper.cc b/chrome/browser/thumbnails/thumbnail_tab_helper.cc
index f8322e76f9a2d9573939dea942a32fe342b8bffb..5b95c8d77bdc23aa6b97a8e651f23ca17fe3fa85 100644
--- a/chrome/browser/thumbnails/thumbnail_tab_helper.cc
+++ b/chrome/browser/thumbnails/thumbnail_tab_helper.cc
@@ -74,6 +74,8 @@ void ProcessCapturedBitmap(scoped_refptr<ThumbnailingContext> context,
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   algorithm->ProcessBitmap(context, base::Bind(&UpdateThumbnail), bitmap);
+
+  context->web_contents->DecrementCapturerCount();

[danakj, 2015/09/17 17:54:14]

Do you not want to do this if the result wasn't SUCCESS?

[shrike, 2015/09/28 21:24:11]

Thank you for catching that. Done.

 }
 
 void AsyncProcessThumbnail(content::WebContents* web_contents,
@@ -196,6 +198,9 @@ void ThumbnailTabHelper::UpdateThumbnailIfNecessary(
     return;
   }
 
+  gfx::Size empty_size;

[danakj, 2015/09/17 17:54:14]

you could just pass the gfx::Size() directly if the context being added by the
name is just that it's empty.

Normally for a temp var like this, I'd want it to refer to the name of the
parameter the function is taking (ie showing the purpose of the variable rather
than what value is inside it).

[shrike, 2015/09/28 21:24:11]

Yeah, you're right about passing it directly. And thank you for the naming tip -
will try to keep that in mind for the future. Done.

+  web_contents->IncrementCapturerCount(empty_size);
+
   scoped_refptr<thumbnails::ThumbnailingAlgorithm> algorithm(
       thumbnail_service->GetThumbnailingAlgorithm());