[Toolbar UI Mac] Fix location bar animation

Pinning the location bar currently uses [[locationBar_ animator] frame], but
this unfortunately relies on inconsistent (and undocumented) behavior of the
animator proxy to return the proper value after animation. Remove the uses of
this, and ensure that the location bar stops animating if it's at the proper
position.

BUG=457162

Review URL: https://codereview.chromium.org/916993004

Cr-Commit-Position: refs/heads/master@{#316713}
(cherry picked from commit 787f5b8906bd97c79dc935b4aec61c4d3017bd14)

TBR=avi@chromium.org

Review URL: https://codereview.chromium.org/938783002

Cr-Commit-Position: refs/branch-heads/2272@{#327}
Cr-Branched-From: 827a380cfdb31aa54c8d56e63ce2c3fd8c3ba4d4-refs/heads/master@{#310958}

• chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm[diff]
• chrome/browser/ui/cocoa/location_bar/autocomplete_text_field.h[diff]
• chrome/browser/ui/cocoa/location_bar/autocomplete_text_field.mm[diff]
• chrome/browser/ui/cocoa/toolbar/toolbar_controller.mm[diff]