tree f1fc7a606f71e1b38b9468a625c30ea2b55dc1ee
parent a90531cd00ad64fb8501c8190f99e068f9d581d6
author Winson Chung <winsonc@google.com> 1561499045 -0700
committer Winson Chung <winsonc@google.com> 1561499045 -0700

Clean up some more refs to thumbnail data

- Always return a copy of the task list to ensure that the model doesn't
  hold refs to the thumbnail data if it was loaded into the same task
- Always clear the task thumbnail data ref once the visibility of the
  task view changes to be invisible

Bug: 132309376
Test: Enter overview scroll to the end of the list, relaunch app and take
      heap dump

Change-Id: I4437fd30172a5fe2a78c111f780163a1e6bbbb54