Merge "base: Add MmapFile as a synonym for MappedFile" am: 727762ef07 Change-Id: I3c28b1afb8ed191a892149f2c2c100502abf4c2c Cr-Mirrored-From: https://chromium.googlesource.com/aosp/platform/system/core Cr-Mirrored-Commit: 26ad5bf069837cfbf1fbeb3b3f9e7659889ba5b8