Fix C4434 warning about 32-bit shift assigned to 64-bits

Fix C4434 warning about 32-bit shift assigned to 64-bits

VS 2015 has a new or louder warning about 32-bit shifts that are then
assigned to a 64-bit target. This type of code triggers it:

int64_t size = 1 << shift_amount;

Because the '1' being shifted is a 32-bit int the result of the shift
will be a 32-bit result, so assigning it to a 64-bit variable is just
misleading.

In this case the code that triggers it is this:

  size_t window_size = static_cast<size_t>(1 << shift_amount);

The destination is a size_t so the warning only shows up on 64-bit
builds and doesn't indicate a real bug. It's curious that the code
had a cast already - presumably to suppress some other warning - but
the cast is not in the ideal place and doesn't avoid this new warning.
Moving the cast allows shift_amount to be log2(size_t) and allows
enabling C4334 in Chromium.

BUG=593448
Committed: https://crrev.com/d81dc49c5be9a9322bdd47aef050a456e759a9f6
Cr-Commit-Position: refs/heads/master@{#12199}

[brucedawson, 2016-03-31 20:56:47]

brucedawson@chromium.org changed reviewers:
+ aluebs@webrtc.org

[brucedawson, 2016-03-31 20:56:48]

Tiny change to let us enable C4334 in Chromium. PTAL.

[aluebs-webrtc, 2016-03-31 22:35:21]

lgtm
Thank you for taking care of this and for the clear explanation! :)

[brucedawson, 2016-03-31 23:23:29]

The CQ bit was checked by brucedawson@chromium.org

[commit-bot: I haz the power, 2016-03-31 23:23:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1849753004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1849753004/1

[commit-bot: I haz the power, 2016-04-01 01:24:18]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-04-01 01:24:19]

Try jobs failed on following builders:
  android_arm64_rel on tryserver.webrtc (JOB_TIMED_OUT, no build URL)
  win_baremetal on tryserver.webrtc (JOB_TIMED_OUT, no build URL)

[brucedawson, 2016-04-01 17:14:57]

The CQ bit was checked by brucedawson@chromium.org

[commit-bot: I haz the power, 2016-04-01 17:14:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1849753004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1849753004/1

[commit-bot: I haz the power, 2016-04-01 17:16:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-04-01 17:16:27]

Description was changed from

==========
Fix C4434 warning about 32-bit shift assigned to 64-bits

VS 2015 has a new or louder warning about 32-bit shifts that are then
assigned to a 64-bit target. This type of code triggers it:

int64_t size = 1 << shift_amount;

Because the '1' being shifted is a 32-bit int the result of the shift
will be a 32-bit result, so assigning it to a 64-bit variable is just
misleading.

In this case the code that triggers it is this:

  size_t window_size = static_cast<size_t>(1 << shift_amount);

The destination is a size_t so the warning only shows up on 64-bit
builds and doesn't indicate a real bug. It's curious that the code
had a cast already - presumably to suppress some other warning - but
the cast is not in the ideal place and doesn't avoid this new warning.
Moving the cast allows shift_amount to be log2(size_t) and allows
enabling C4334 in Chromium.

BUG=593448
==========

to

==========
Fix C4434 warning about 32-bit shift assigned to 64-bits

VS 2015 has a new or louder warning about 32-bit shifts that are then
assigned to a 64-bit target. This type of code triggers it:

int64_t size = 1 << shift_amount;

Because the '1' being shifted is a 32-bit int the result of the shift
will be a 32-bit result, so assigning it to a 64-bit variable is just
misleading.

In this case the code that triggers it is this:

  size_t window_size = static_cast<size_t>(1 << shift_amount);

The destination is a size_t so the warning only shows up on 64-bit
builds and doesn't indicate a real bug. It's curious that the code
had a cast already - presumably to suppress some other warning - but
the cast is not in the ideal place and doesn't avoid this new warning.
Moving the cast allows shift_amount to be log2(size_t) and allows
enabling C4334 in Chromium.

BUG=593448

Committed: https://crrev.com/d81dc49c5be9a9322bdd47aef050a456e759a9f6
Cr-Commit-Position: refs/heads/master@{#12199}
==========

[commit-bot: I haz the power, 2016-04-01 17:16:28]

Patchset 1 (id:??) landed as
https://crrev.com/d81dc49c5be9a9322bdd47aef050a456e759a9f6
Cr-Commit-Position: refs/heads/master@{#12199}