If we are animating the cursor it is possible to drop an IPC that didn't
belong to us on the floor.
When animating, we post messages to main thread manually and return true because we assume that they are messages we know how to handle. If the message is not a cursor message that a main thread handler knows how to deal with, returning true means we effectively drop it on the floor. This patch returns false immediately if the message is not of a known type.
BUG=
Review URL: https://codereview.chromium.org/
843223002
Cr-Commit-Position: refs/heads/master@{#310940}