Declaring the weak_ptr_factory in proper order.

Cleaning up weak_ptr_factory destruction order in "src/chrome/browser/ui"
module. WeakPtrFactory should remain the last member so it'll be destroyed and
invalidate its weak pointers before any other members are destroyed.

BUG=303818

Review URL: https://codereview.chromium.org/603383003

Cr-Commit-Position: refs/heads/master@{#296898}
1 file changed