Add PrerenderLocalPredictor, which will eventually perform

chrome/browser/history/history_types.h

Index: chrome/browser/history/history_types.h
===================================================================
--- chrome/browser/history/history_types.h	(revision 131579)
+++ chrome/browser/history/history_types.h	(working copy)
@@ -751,6 +751,20 @@
   history::IconType icon_type;
 };
 
+// Abbreviated information about a visit.
+struct BriefVisitInfo {
+  URLID url_id;
+  base::Time time;
+  content::PageTransition transition;
+};
+
+// An observer of VisitDatabase.
+class VisitDatabaseObserver {
+ public:
+  virtual ~VisitDatabaseObserver() {}
+  virtual void OnAddVisit(BriefVisitInfo info) = 0;

[brettw, 2012/04/20 22:21:50]

I'd probably change all the places where you pass this to be by const ref
(including in history.h). Although this case is pretty borderline (looks like 20
bytes) I think people are more used to that and if we add onto the struct we
won't have to change everything.

[tburkard, 2012/04/20 22:56:44]

Wouldn't that be problematic, since the BriefVisitInfo is on the stack when it
is generated, and wouldnt be around long enough for the callback on the other
thread of the observer?

On 2012/04/20 22:21:50, brettw wrote:

[brettw, 2012/04/23 17:52:54]

PostTask knows to copy pass-by-ref args to other threads. So pass by ref should
be OK as far as I know.

[tburkard, 2012/04/23 18:24:11]

Done.

+};
+
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_TYPES_H_