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);
+    // When the old text was empty, we don't bother selecting the new text.
+    // You might think we could reach here if the user has deleted the previous
+    // URL, but in that case the model will see that user input is in progress
+    // and return false from UpdatePermanentText() (so we won't reach here),
+    // unless we don't have focus, in which case we don't care anyway because
+    // re-focusing the omnibox will modify the selection regardless.  The only
+    // time we actually reach here with empty text is when the user was on the
+    // NTP and clicked something on the page to navigate, in which case the
+    // omnibox shouldn't have focus anyway, and selecting all will at best do
+    // nothing and at worst cause problems like reversing the URL.
+    if (was_select_all && (sel.cpMin != sel.cpMax))
+      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();
 }