Cache the current WebPreferences on RenderViewHostImpl (try #2).

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index b40774f564202ba9f137a2a36546dcea6b74e130..13c487e6d8533413c025624317b722cda43193a8 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -3825,7 +3825,7 @@ bool WebContentsImpl::AddMessageToConsole(int32 level,
                                         source_id);
 }
 
-WebPreferences WebContentsImpl::GetWebkitPrefs() {
+WebPreferences WebContentsImpl::ComputeWebkitPrefs() {
   // We want to base the page config off of the actual URL, rather than the
   // virtual URL.
   // TODO(nasko): Investigate how to remove the GetActiveEntry usage here,
@@ -3833,7 +3833,7 @@ WebPreferences WebContentsImpl::GetWebkitPrefs() {
   GURL url = controller_.GetActiveEntry()
       ? controller_.GetActiveEntry()->GetURL() : GURL::EmptyGURL();
 
-  return GetRenderManager()->current_host()->GetWebkitPrefs(url);
+  return GetRenderManager()->current_host()->ComputeWebkitPrefs(url);
 }
 
 int WebContentsImpl::CreateSwappedOutRenderView(