Always call super.onCreate().  Always.

Bug 12991134

(cherrypick of commit 9d6376a1d88ab5b3a41ee4400e3aaa4c4ee69e2a)

Change-Id: Ife16ef93408253e3318a06dc0206ab4b88c7f367
Don't allow MemoryFiles of negative length.

Prevents us from converting a (signed) jint into an
(unsigned) size_t and having horrible things happen.

Change-Id: I0f04e2eb9852ae7fc49b435fd0974f56e86751a4