Remove views::NativeTextfieldWrapper, start class cleanup.

A first step towards combining views::Textfield and views::NativeTextfieldViews.
Remove NativeTextfieldWrapper, use NativeTextfieldViews directly.
Remove, inline, and simplify some minimal functionality.
Cleanup some related code/comments/tests.

BUG=131660
TEST=No build breaks, no behavior changes, no regressions.
R=sky@chromium.org

Review URL: https://codereview.chromium.org/105713004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241783 0039d316-1c4b-4281-b951-d872f2087c98
TELEMETRY: Move frame-rate metrics from measurement to metric

Otherwise these are duplicated in the TimelineMetric.

BUG=321439

Review URL: https://codereview.chromium.org/112893003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241784 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241783
SVN changes up to revision 241784