Fix NTP thumbnail generation

chrome/browser/thumbnails/thumbnail_tab_helper.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/thumbnails/thumbnail_tab_helper.h"
 
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/thumbnails/thumbnail_service.h"
 #include "chrome/browser/thumbnails/thumbnail_service_factory.h"
@@ skipping 56 matching lines @@
                            const SkBitmap& bitmap,
                            content::ReadbackResponse response) {
   if (response != content::READBACK_SUCCESS)
     return;
 
   // On success, we must be on the UI thread (on failure because of shutdown we
   // are not on the UI thread).
   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,
                            scoped_refptr<ThumbnailingContext> context,
                            scoped_refptr<ThumbnailingAlgorithm> algorithm) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   RenderWidgetHost* render_widget_host = web_contents->GetRenderViewHost();
   content::RenderWidgetHostView* view = render_widget_host->GetView();
   if (!view)
     return;
@@ skipping 102 matching lines @@
 
   scoped_refptr<thumbnails::ThumbnailService> thumbnail_service =
       ThumbnailServiceFactory::GetForProfile(profile);
 
   // Skip if we don't need to update the thumbnail.
   if (thumbnail_service.get() == NULL ||
       !thumbnail_service->ShouldAcquirePageThumbnail(url)) {
     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());
 
   scoped_refptr<ThumbnailingContext> context(new ThumbnailingContext(
       web_contents, thumbnail_service.get(), load_interrupted_));
   AsyncProcessThumbnail(web_contents, context, algorithm);
 }
 
 void ThumbnailTabHelper::RenderViewHostCreated(
     content::RenderViewHost* renderer) {
@@ skipping 10 matching lines @@
         content::NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
         content::Source<RenderWidgetHost>(renderer));
   }
 }
 
 void ThumbnailTabHelper::WidgetHidden(RenderWidgetHost* widget) {
   if (!enabled_)
     return;
   UpdateThumbnailIfNecessary(web_contents());
 }