Do not commit InstantLoader server redirects till the page supports instant.

chrome/browser/instant/instant_loader.cc

Index: chrome/browser/instant/instant_loader.cc
diff --git a/chrome/browser/instant/instant_loader.cc b/chrome/browser/instant/instant_loader.cc
index c6e6874e5473509f431f41f34e479e93a1524e95..10246909e6ffc12aacd52626a9476fd3a8c822f0 100644
--- a/chrome/browser/instant/instant_loader.cc
+++ b/chrome/browser/instant/instant_loader.cc
@@ -19,6 +19,7 @@
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_widget_host_view.h"
+#include "content/public/browser/resource_request_details.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "content/public/browser/web_contents_view.h"
 #include "ipc/ipc_message.h"
@@ -326,7 +327,9 @@ void InstantLoader::RenderViewGone() {
 }
 
 void InstantLoader::AboutToNavigateMainFrame(const GURL& url) {
-  controller_->InstantLoaderAboutToNavigateMainFrame(url);
+  controller_->InstantLoaderAboutToNavigateMainFrame(
+      url, url == expected_redirect_);
+  expected_redirect_ = GURL();
 }
 
 void InstantLoader::NavigateToURL(const GURL& url,
@@ -338,6 +341,13 @@ void InstantLoader::NavigateToURL(const GURL& url,
 void InstantLoader::Observe(int type,
                             const content::NotificationSource& source,
                             const content::NotificationDetails& details) {
+  if (type == content::NOTIFICATION_RESOURCE_RECEIVED_REDIRECT) {
+    content::ResourceRedirectDetails* resource_redirect_details =
+        content::Details<content::ResourceRedirectDetails>(details).ptr();
+    if (resource_redirect_details->resource_type == ResourceType::MAIN_FRAME)
+      expected_redirect_ = resource_redirect_details->new_url;
+  }
+
 #if defined(OS_MACOSX)
   if (type == content::NOTIFICATION_RENDER_VIEW_HOST_CHANGED) {
     if (content::RenderWidgetHostView* rwhv =
@@ -397,6 +407,9 @@ void InstantLoader::SetupPreviewContents() {
                  content::Source<content::NavigationController>(
                      &contents_->GetController()));
 #endif
+
+  registrar_.Add(this, content::NOTIFICATION_RESOURCE_RECEIVED_REDIRECT,
+                 content::Source<content::WebContents>(contents()));
 }
 
 void InstantLoader::CleanupPreviewContents() {