Ensure that PageID's of prerendered pages do not exceed the Page ID of the

chrome/browser/prerender/prerender_contents.cc

Index: chrome/browser/prerender/prerender_contents.cc
===================================================================
--- chrome/browser/prerender/prerender_contents.cc	(revision 86289)
+++ chrome/browser/prerender/prerender_contents.cc	(working copy)
@@ -138,7 +138,8 @@
       final_status_(FINAL_STATUS_MAX),
       prerendering_has_started_(false),
       child_id_(-1),
-      route_id_(-1) {
+      route_id_(-1),
+      starting_page_id_(-1) {
   DCHECK(prerender_manager != NULL);
 }
 
@@ -262,11 +263,12 @@
     // So that history merging will work, get the max page ID
     // of the old page, and add a safety margin of 10 to it (for things
     // such as redirects).
-    int32 max_page_id = source_tc->GetMaxPageID();
-    if (max_page_id != -1) {
-      prerender_contents_->controller().set_max_restored_page_id(
-          max_page_id + 10);
-    }
+    starting_page_id_ = source_tc->GetMaxPageID();
+    if (starting_page_id_ < 0)

[dominich, 2011/05/23 17:05:15]

As -1 has a special meaning and we don't expect < -1, perhaps this should be ==
-1.

[tburkard, 2011/05/23 17:07:42]

Page ID's should be positive.  So I just wanted to use defensive programing.  If
it is say -100 for whatever reason, I'd rather set it to 10 to ensure the page
id of the prerender will be positive, rather than ignore it or crash and use an
invalid negative page id.

On 2011/05/23 17:05:15, dominic wrote:

+      starting_page_id_ = 0;
+    starting_page_id_ += 10;

[dominich, 2011/05/23 17:05:15]

Can you make this 10 a constant?

[tburkard, 2011/05/23 17:07:42]

Done.

+    prerender_contents_->controller().set_max_restored_page_id(
+        starting_page_id_);
 
     tab_contents_delegate_.reset(new TabContentsDelegateImpl(this));
     new_contents->set_delegate(tab_contents_delegate_.get());