[Mac] Created Suggested Text Touch Bar

When text is selected in a textfield, the touch bar displays options
to replace the selected text. Clicking on one of the options will
replace the selected text with the selected option.

Currently, there are no functional unit tests for the suggested text
touch bar. As functionality is fleshed out, unit tests will be

A new folder (chrome/browser/ui/cocoa/touchbar) was created to house all
files related to the Mac touch bar. The
CreditCardAutofillTouchBarController files and the
WebTextfieldTouchBarController files were moved to this new folder.
Dependencies and header guards were updated to reflect this change.

New files:
  - suggested_text_touch_bar_controller.h
  - suggested_text_touch_bar_controller.mm
  - suggested_text_touch_bar_controller_browsertest.mm
Moved files:
  - credit_card_autofill_touch_bar_controller.h
  - credit_card_autofill_touch_bar_controller.mm
  - credit_card_autofill_touch_bar_controller_unittest.mm
  - web_textfield_touch_bar_controller.h
  - web_textfield_touch_bar_controller.mm

BUILD files were updated to accomodate the change in location for the
moved files and to include the new files.

WebContentsImpl, WebContentsDelegate, and WebContentsObserver were
modified so that the SuggestedTextTouchBarController can observe
TextInputManager for a change in text selection.

A feature flag SuggestedTextTouchBar was created and added to
chrome://about so that the new touch bar is disabled by default and
can be enabled via command line or chrome://flags with the flag

This CL includes the following browser tests for
  - SetTextTest
  - TouchBarTest
  - TextSelectionChangedTest

Bug: 717553
Change-Id: Icdd796c5d7ff6f67598b58c6c6c8c17a6a85d004
Reviewed-on: https://chromium-review.googlesource.com/1069495
Commit-Queue: Tessa Nijssen <tnijssen@google.com>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Sarah Chan <spqchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565799}
21 files changed