views: Convert IsFocusable() to just focusable() since it's just a simple accessor.

ui/views/controls/textfield/textfield.cc

Index: ui/views/controls/textfield/textfield.cc
diff --git a/ui/views/controls/textfield/textfield.cc b/ui/views/controls/textfield/textfield.cc
index ffbabe0293fd7f5bf30d1ed85dd038742815a80e..e2beb4d9168ecf5c4bbaf06eb79702a8e6b00c66 100644
--- a/ui/views/controls/textfield/textfield.cc
+++ b/ui/views/controls/textfield/textfield.cc
@@ -92,6 +92,7 @@ TextfieldController* Textfield::GetController() const {
 
 void Textfield::SetReadOnly(bool read_only) {
   read_only_ = read_only;
+  set_focusable(!read_only);
   if (native_wrapper_) {
     native_wrapper_->UpdateReadOnly();
     native_wrapper_->UpdateTextColor();
@@ -330,10 +331,6 @@ gfx::Size Textfield::GetPreferredSize() {
                        insets.width(), font_.GetHeight() + insets.height());
 }
 
-bool Textfield::IsFocusable() const {
-  return View::IsFocusable() && !read_only_;
-}
-
 void Textfield::AboutToRequestFocusFromTabTraversal(bool reverse) {
   SelectAll();
 }