Don't mess with omnibox selection on update when the omnibox doesn't have focus.

chrome/browser/ui/views/omnibox/omnibox_view_win.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/omnibox/omnibox_view_win.h"
 
 #include <algorithm>
 #include <locale>
 #include <string>
 
@@ skipping 628 matching lines @@
     // we _were_ switching tabs, the RevertAll() above already drew the new
     // permanent text.)
 
     // Tweak: if the user had all the text selected, select all the new text.
     // This makes one particular case better: the user clicks in the box to
     // change it right before the permanent URL is changed.  Since the new URL
     // is still fully selected, the user's typing will replace the edit contents
     // as they'd intended.
     CHARRANGE sel;
     GetSelection(sel);
-    const bool was_reversed = (sel.cpMin > sel.cpMax);
-    const bool was_select_all = (sel.cpMin != sel.cpMax) &&
-      IsSelectAllForRange(sel);
+    const bool was_select_all = IsSelectAllForRange(sel);
 
     RevertAll();
 
-    if (was_select_all)
-      SelectAll(was_reversed);
+    // Only select all when we have focus.  If we don't have focus, selecting
+    // all is unnecessary since the selection will change on regaining focus,
+    // and can in fact cause artifacts, e.g. if the user is on the NTP and
+    // clicks a link to navigate, causing |was_select_all| to be vacuously true
+    // for the empty omnibox, and we then select all here, leading to the
+    // trailing portion of a long URL being scrolled into view.  We could try
+    // and address cases like this, but it seems better to just not muck with
+    // things when the omnibox isn't focused to begin with.
+    if (was_select_all && model()->has_focus())
+      SelectAll(sel.cpMin > sel.cpMax);
   } else if (changed_security_level) {
     // Only the security style changed, nothing else.  Redraw our text using it.
     EmphasizeURLComponents();
   }
 }
 
 void OmniboxViewWin::OpenMatch(const AutocompleteMatch& match,
                                WindowOpenDisposition disposition,
                                const GURL& alternate_nav_url,
                                size_t selected_line) {
@@ skipping 2158 matching lines @@
   return (rect.left - client_rect.left) + (client_rect.right - rect.right);
 }
 
 int OmniboxViewWin::WidthNeededToDisplay(const string16& text) const {
   // Use font_.GetStringWidth() instead of PosFromChar(GetTextLength()) because
   // PosFromChar() is apparently buggy. In both LTR UI and RTL UI with
   // left-to-right layout, PosFromChar(i) might return 0 when i is greater than
   // 1.
   return font_.GetStringWidth(text) + GetHorizontalMargin();
 }