Document weak pointer factory constructor requirement.

Review URL: https://codereview.chromium.org/1336763005

Cr-Commit-Position: refs/heads/master@{#348966}


CrOS-Libchrome-Original-Commit: d5144064af15ce8e24589891c326400a43c27ce0
1 file changed
tree: 9e58a8ebfc2095522765884d1f5bcb84d3de478b
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/