Allow SiteInstance for about:blank in new tab to be reused.

content/browser/tab_contents/tab_contents.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 "content/browser/tab_contents/tab_contents.h"
 
 #include <cmath>
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
@@ skipping 1733 matching lines @@
 void TabContents::RenderViewDeleted(RenderViewHost* rvh) {
   render_manager_.RenderViewDeleted(rvh);
   FOR_EACH_OBSERVER(WebContentsObserver, observers_, RenderViewDeleted(rvh));
 }
 
 void TabContents::DidNavigate(RenderViewHost* rvh,
                               const ViewHostMsg_FrameNavigate_Params& params) {
   if (content::PageTransitionIsMainFrame(params.transition))
     render_manager_.DidNavigateMainFrame(rvh);
 
-  // Update the site of the SiteInstance if it doesn't have one yet.
-  if (!static_cast<SiteInstanceImpl*>(GetSiteInstance())->HasSite())
+  // Update the site of the SiteInstance if it doesn't have one yet, unless
+  // this is for about:blank.  In that case, the SiteInstance can still be
+  // considered unused until a navigation to a real page.
+  if (!static_cast<SiteInstanceImpl*>(GetSiteInstance())->HasSite() &&
+      params.url != GURL(chrome::kAboutBlankURL)) {
     static_cast<SiteInstanceImpl*>(GetSiteInstance())->SetSite(params.url);
+  }
 
   // Need to update MIME type here because it's referred to in
   // UpdateNavigationCommands() called by RendererDidNavigate() to
   // determine whether or not to enable the encoding menu.
   // It's updated only for the main frame. For a subframe,
   // RenderView::UpdateURL does not set params.contents_mime_type.
   // (see http://code.google.com/p/chromium/issues/detail?id=2929 )
   // TODO(jungshik): Add a test for the encoding menu to avoid
   // regressing it again.
   if (content::PageTransitionIsMainFrame(params.transition))
@@ skipping 524 matching lines @@
   encoding_ = content::GetContentClient()->browser()->
       GetCanonicalEncodingNameByAliasName(encoding);
 }
 
 void TabContents::CreateViewAndSetSizeForRVH(RenderViewHost* rvh) {
   RenderWidgetHostView* rwh_view = GetView()->CreateViewForWidget(rvh);
   // Can be NULL during tests.
   if (rwh_view)
     rwh_view->SetSize(GetView()->GetContainerSize());
 }