Reland Merge NativeTextfieldViews into views::Textfield.

Reland Merge NativeTextfieldViews into views::Textfield.

Reverted in r244402 for Linux-Aura test failures.
I fixed Ctrl+Shift+Delete/Backspace behavior on Linux here.

Consolidate the split textfield code into Textfield.
No behavior changes (except STYLE_LOWERCASE GetText nit).
Use the underlying model's text and font_list storage.
Remove unused code; rename TextfieldViewsModel::text().
Revise gesture and command handling.

Skip NotifyAccessibilityEvent native behavior without widget.
(No HWND for Views not yet added to view hierarchy)

Make TouchEditable::GetNativeView const; avoids conflict.
Fix includes, forward decls, Font[List] usage, tests.

Ideas for followup cleanup and refactoring:
-Cleanup View overrides decl/def order.
-Refactor RemoveBorder, SetHorizontalMargins, etc.
-Try to use composition instead of inheritance.
-Remove textfield style ctor; refactor style code.
-Remove STYLE_LOWERCASE functionality (one user).
-Replace placeholder DrawStringRect with a Label view.
-Cleanup CreateTouchSelectionControllerAndNotifyIt, etc.
-Cleanup SetColor/SetTextColor, etc.

BUG=131660
TEST=No textfield behavior/appearance regressions.
TBR=sky@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=244436

[commit-bot: I haz the power, 2014-01-12 03:15:13]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msw@chromium.org/135863002/70001

[commit-bot: I haz the power, 2014-01-12 06:12:02]

Change committed as 244436