Allow users to perform queries in the omnibox which begin with a search

shortcut.

Previously, if a user had (for example) configured a search shortcut of 'cs' which
went to cs.chromium.org, they would be unable to (easily) start a query in the
omnibox starting with 'cs'. Now, backspacing the keyword leaves the space after
the keyword, allowing the user to continue typing without reenabling keyword
mode.

BUG=393371
NOTRY=true
R=pkasting@chromium.org
TEST=type 'google.com ' into the omnibar and it should enter keyword mode.
Press backspace and 'google.com ' will be left in the omnibar, rather than
'google.com'.

Review URL: https://codereview.chromium.org/477873002

Cr-Commit-Position: refs/heads/master@{#322429}

AUTHORS

@@ -291,6 +291,7 @@ Laszlo Radanyi <bekkra@gmail.com>
 Lauren Yeun Kim <lauren.yeun.kim@gmail.com>
 Lauri Oherd <lauri.oherd@gmail.com>
 Leith Bade <leith@leithalweapon.geek.nz>
+Lenny Khazan <lenny.khazan@gmail.com>
 Li Yin <li.yin@intel.com>
 Lidwine Genevet <lgenevet@cisco.com>
 Lionel Landwerlin <lionel.g.landwerlin@intel.com>

chrome/browser/ui/omnibox/omnibox_edit_model.cc

@@ -880,14 +880,17 @@ void OmniboxEditModel::ClearKeyword(const base::string16& visible_text) {
   autocomplete_controller()->Stop(false);
   omnibox_controller_->ClearPopupKeywordMode();
 
-  const base::string16 window_text(keyword_ + visible_text);
+  // Add a space after the keyword to allow the user to continue typing without
+  // re-enabling keyword mode.
+  const base::string16 window_text =
+      keyword_ + base::ASCIIToUTF16(" ") + visible_text;
 
   // Only reset the result if the edit text has changed since the
   // keyword was accepted, or if the popup is closed.
   if (just_deleted_text_ || !visible_text.empty() ||
       !(popup_model() && popup_model()->IsOpen())) {
     view_->OnBeforePossibleChange();
-    view_->SetWindowTextAndCaretPos(window_text.c_str(), keyword_.length(),
+    view_->SetWindowTextAndCaretPos(window_text.c_str(), keyword_.length() + 1,
         false, false);
     keyword_.clear();
     is_keyword_hint_ = false;
@@ -897,7 +900,7 @@ void OmniboxEditModel::ClearKeyword(const base::string16& visible_text) {
                                 // longer.
   } else {
     is_keyword_hint_ = true;
-    view_->SetWindowTextAndCaretPos(window_text.c_str(), keyword_.length(),
+    view_->SetWindowTextAndCaretPos(window_text.c_str(), keyword_.length() + 1,
         false, true);
   }