Merge "Revert "Icon: make Icon's Bitmaps immutable"" into tm-dev am: 4e8c47ef am: 1837e9ec

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17919920



Change-Id: Ic2db312318d0ad882da1a9173dab72c097ee16ee
Ignore-AOSP-First: this is an automerge
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>