Revert "MediaScanner: delete abnormal elements in prescan procedure."

This reverts commit ccdb29e9d93305dae12375b10db658d2fe2ffe2b.
Revert "Remove unnecessary reference in ActivityManagerService."

This reverts commit 31c4939275ca5af0b0195dd0b2f6b7fd258ac89f.
Revert "Disable usage of WAL in DatabaseHelper"

This reverts commit cbe726b38249d80f45cb07118c9de4805eaee1dc.
Revert "remove leak WaitResult List in startActivityMayWait"

This reverts commit 1de5c594dbcab8f42f9881a71a5390ac4a81456a.
Revert "Framework/base: Added synchronization block to avoid race condition"

This reverts commit cefb8b38c50c640123dcfb91f17cfd19f589b3b7.