Reland "Upconvert various types to int.", common_audio portion.

Reland "Upconvert various types to int.", common_audio portion.

This reverts portions of commit cb180976dd0e9672cde4523d87b5f4857478b5e9, which
reverted commit 83ad33a8aed1fb00e422b6abd33c3e8942821c24.  Specifically, the
files in webrtc/common_audio/ are relanded.

The original commit message is below:

Upconvert various types to int.

Per comments from HL/kwiberg on https://webrtc-codereview.appspot.com/42569004 , when there is existing usage of mixed types (int16_t, int, etc.), we'd prefer to standardize on larger types like int and phase out use of int16_t.

Specifically, "Using int16 just because we're sure all reasonable values will fit in 16 bits isn't usually meaningful in C."

This converts some existing uses of int16_t (and, in a few cases, other types such as uint16_t) to int (or, in a few places, int32_t).  Other locations will be converted to size_t in a separate change.

BUG=none
TBR=andrew

Committed: https://crrev.com/15b58eea282b03b6347c64714079691f55e6097f
Cr-Commit-Position: refs/heads/master@{#9425}

[Peter Kasting, 2015-06-12 01:00:05]

pkasting@chromium.org changed reviewers:
+ andrew@webrtc.org

[Peter Kasting, 2015-06-12 02:41:04]

Committed patchset #1 (id:1) manually as
15b58eea282b03b6347c64714079691f55e6097f (presubmit successful).

[commit-bot: I haz the power, 2015-06-12 02:41:10]

Patchset 1 (id:??) landed as
https://crrev.com/15b58eea282b03b6347c64714079691f55e6097f
Cr-Commit-Position: refs/heads/master@{#9425}