Remove null checking in JavaObjectWeakGlobalRef ctr

It is legal to create a weak reference to null. Removes the defensive
null checking being done in the constructors.

BUG=649407

Review-Url: https://codereview.chromium.org/2389403002
Cr-Commit-Position: refs/heads/master@{#423143}


CrOS-Libchrome-Original-Commit: 48678a7b6e9087357262f8acee9df186b337d706
1 file changed
tree: 46ee20e4703b2fadeab0dea784397607081d9119
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/