When a new tab is opened (either the new tab page via Ctrl+T or pressing the new tab button) or an address is opened from the address bar in a new tab (by pressing Alt+Enter), the opener is remembered briefly, allowing quick lookup in a new tab without disrupting the z-order experience.

Full explanation in bug:

B=1266404

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@330 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 24 insertions, 8 deletions

diff --git a/chrome/browser/browser.cc b/chrome/browser/browser.cc
index 7a0bbb0..47299ce 100644
--- a/chrome/browser/browser.cc
+++ b/chrome/browser/browser.cc
@@ -589,14 +589,30 @@ void Browser::OpenURLFromTab(TabContents* source,
         transition == PageTransition::AUTO_BOOKMARK ||
         transition == PageTransition::GENERATED ||
         transition == PageTransition::START_PAGE) {
-      // If the user navigates the current tab to another page in any way other
-      // than by clicking a link, we want to pro-actively forget all TabStrip
-      // opener relationships since we assume they're beginning a different
-      // task by reusing the current tab.
-      tabstrip_model_.ForgetAllOpeners();
-      // In this specific case we also want to reset the group relationship,
-      // since it is now technically invalid.
-      tabstrip_model_.ForgetGroup(current_tab);
+      // Don't forget the openers if this tab is a New Tab page opened at the
+      // end of the TabStrip (e.g. by pressing Ctrl+T). Give the user one
+      // navigation of one of these transition types before resetting the
+      // opener relationships (this allows for the use case of opening a new
+      // tab to do a quick look-up of something while viewing a tab earlier in
+      // the strip). We can make this heuristic more permissive if need be.
+      // TODO(beng): (http://b/1306495) write unit tests for this once this
+      //             object is unit-testable.
+      int current_tab_index =
+          tabstrip_model_.GetIndexOfTabContents(current_tab);
+      bool forget_openers = 
+          !(current_tab->type() == TAB_CONTENTS_NEW_TAB_UI &&
+          current_tab_index == (tab_count() - 1) &&
+          current_tab->controller()->GetEntryCount() == 1);
+      if (forget_openers) {
+        // If the user navigates the current tab to another page in any way
+        // other than by clicking a link, we want to pro-actively forget all
+        // TabStrip opener relationships since we assume they're beginning a
+        // different task by reusing the current tab.
+        tabstrip_model_.ForgetAllOpeners();
+        // In this specific case we also want to reset the group relationship,
+        // since it is now technically invalid.
+        tabstrip_model_.ForgetGroup(current_tab);
+      }
     }
     current_tab->controller()->LoadURL(url, transition);
     // The TabContents might have changed as part of the navigation (ex: new tab