[ObjC ARC] Converts ios/chrome/browser/ui/history:history to ARC.
Semi-autogenerated ARCMigrate commit.
Notable issues:
* Since one of the weak_nsobjects is exposed in a header and I change it to a __weak instead, converted two unit tests to ARC alongside this.
* Fixed some assignments of newly created views to weak properties by introducing an intermediate local variable to retain the view until it's added as subview.
BUG=624363
TEST=None
Review-Url: https://codereview.chromium.org/2624963003
Cr-Commit-Position: refs/heads/master@{#443240}
26 files changed
