Ensure that the browser’s copy of page id is in sync with the renderer’s.

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 a86d316644ea25d8745dc10dfef98626ee641106..b0ba217db4f639e602c74d20934e8d5a048d95dc 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "base/command_line.h"
+#include "base/debug/crash_logging.h"
 #include "base/debug/trace_event.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ -3588,8 +3589,32 @@ void WebContentsImpl::RenderViewDeleted(RenderViewHost* rvh) {
 }
 
 void WebContentsImpl::UpdateState(RenderViewHost* rvh,
+                                  int32 rvh_page_id,
                                   int32 page_id,
                                   const PageState& page_state) {
+  if (rvh_page_id != page_id) {
+    base::debug::SetCrashKeyValue("renderer_page_id",
+                                  base::IntToString(page_id));
+    base::debug::SetCrashKeyValue("browser_page_id",
+                                  base::IntToString(rvh_page_id));
+    NavigationEntryImpl* entry = NavigationEntryImpl::FromNavigationEntry(
+        controller_.GetLastCommittedEntry());
+    // The question being answered here is: when there is a page id mismatch
+    // between the renderer and the browser, which value (if either) matches
+    // that of the last committed entry?
+    if (entry) {
+      if (entry->site_instance() == rvh->GetSiteInstance()) {
+        base::debug::SetCrashKeyValue("last_committed_page_id",
+                                      base::IntToString(entry->GetPageID()));
+      } else {
+        base::debug::SetCrashKeyValue("last_committed_page_id",
+                                      "site instance mismatch");
+      }
+    } else {
+      base::debug::SetCrashKeyValue("last_committed_page_id", "no entry");
+    }
+    CHECK(false);
+  }
   // Ensure that this state update comes from either the active RVH or one of
   // the swapped out RVHs.  We don't expect to hear from any other RVHs.
   // TODO(nasko): This should go through RenderFrameHost.