Views::Textfield: Decouple handling of menu and text editing commands.

Currently, all text editing commands are routed through IsCommandIdEnabled() and
ExecuteCommand(int command_id, int event_flags) which are
ui::SimpleMenuModel::Delegate overrides. These were probably just meant to be
used for menu actions, but are currently also being used for text editing
commands.

This CL modifies IsCommandIdEnabled and
ExecuteCommand(int command_id, int event_flags) in views::Textfield and its
subclass OmniboxViewViews, to only handle menu actions. To handle text editing
commands, IsEditCommandEnabled (overriden from ui::TextInputClient) is used.
Analogous to ExecuteCommand, a protected virtual method ExecuteEditCommand is
added to views::Textfield to execute text editing commands. Also, since it's
confusing to have both an overloaded and overriden ExecuteCommand method, the
overloaded version is removed.

A helper function bool `IsMenuCommand(int)` is also added which will be updated
in a follow-up (crrev.com/2027133002/) to return a text editing command  enum
rather than a bool. (i.e. `ui::TextEditCommand
GetTextEditCommandFromMenuCommand(int command_id)`).

This is first in series of CLs to replace resource ids with a
ui::TextEditCommand enum for text editing commands in views::Textfield.

Link to complete patch - http://crrev.com/2029733003

BUG=586985

Review-Url: https://codereview.chromium.org/2031433002
Cr-Commit-Position: refs/heads/master@{#400909}
5 files changed