[omnibox] Break out SetCaretPos() method and enhance browser test

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

Index: chrome/browser/ui/views/omnibox/omnibox_view_views.cc
diff --git a/chrome/browser/ui/views/omnibox/omnibox_view_views.cc b/chrome/browser/ui/views/omnibox/omnibox_view_views.cc
index 6add5dda5be118436629c2afa3534209146d6c72..521eeee2e875a990dd622af1aadbb7b5029ce81e 100644
--- a/chrome/browser/ui/views/omnibox/omnibox_view_views.cc
+++ b/chrome/browser/ui/views/omnibox/omnibox_view_views.cc
@@ -429,6 +429,10 @@ void OmniboxViewViews::SetWindowTextAndCaretPos(const base::string16& text,
     TextChanged();
 }
 
+void OmniboxViewViews::SetCaretPos(size_t caret_pos) {
+  SelectRange(gfx::Range(caret_pos, caret_pos));
+}
+
 bool OmniboxViewViews::IsSelectAll() const {
   // TODO(oshima): IME support.
   return text() == GetSelectedText();