Eliminate box reordering in media::mp4::BoxReader.

Eliminate box reordering in media::mp4::BoxReader.

ScanChildren() will reorder boxes based on their box type. The
SampleDescription box is the only supported box which is agnostic about
the box type of its children, and it is sensitive to the child order.
This patch modifies ReadAllChildren() to read children in order without
first invoking ScanChildren().

R=acolwell
BUG=
TEST=BoxReaderTest.ReadAllChildrenTest


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=158046

[acolwell GONE FROM CHROMIUM, 2012-09-21 16:41:03]

LGTM

[commit-bot: I haz the power, 2012-09-21 17:19:57]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/strobe@google.com/10938034/1

[commit-bot: I haz the power, 2012-09-21 19:34:29]

Change committed as 158046