Use COMPONENT_EXPORT for mojo/public/cpp/base targets

Switches targets in mojo/public/cpp/base to use the new
COMPONENT_EXPORT macro from base.

Also moves BigString's mojom traits sources directly into the mojom
typemap since they aren't shared with any other targets. This means
they can be exported as part of the mojom component itself.

Also s/struct_traits/mojom_traits/g

TBR=jam@chromium.org

Bug: None
Change-Id: I55a051542e15df2ca12d13f1933a13361aa89e72
Reviewed-on: https://chromium-review.googlesource.com/899769
Commit-Queue: Ken Rockot <rockot@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534280}

CrOS-Libchrome-Original-Commit: bdcddc95ab232c5fcc45543fac16be313b3cf60d
13 files changed
tree: 92daa80b7e9d05b7091091e4b908d7ab3dba0ac0
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/