Cherry-pick: Clear m_lastImageId for software compositor

Cherry-pick with conflict of


Original description:

When android webview swith to software only mode, all mailboxes are
returned to Canvas2DLayerBridge. In this case, if the canvas is static,
then prepareMailbox will never return a new mailbox. So clear m_lastImageId
in this case.

BUG: 13328348

Change-Id: I5d8ec2cb5c613b0991bc66df29a0ff17441f018c
2 files changed