Make various gfx classes more amenable to use as compile-time constants.

Specifically, this means marking most constructors and simple accessors as
constexpr.  It also means removing the explicit empty destructors, since that
can qualify as a nontrivial destructor and bung things up.  (If we really want
to explicitly declare these, the right way would be to use "= default".)

This also adds some missing operators to the Insets classes.  I needed one of
these, and the style guide says to overload all related operators when
overloading one.

BUG=none
TEST=none
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
R=danakj@chromium.org

Review URL: https://codereview.chromium.org/2051343002 .

Cr-Commit-Position: refs/heads/master@{#399815}


CrOS-Libchrome-Original-Commit: 275539a60ec716bea022200fa650a409772a81bf
18 files changed
tree: aaef0259a080eca648a90e01735766285a0fb3f9
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/