Use "share_screenshot_as_stream" instead of Intent.EXTRA_STREAM

Use "share_screenshot_as_stream" instead of Intent.EXTRA_STREAM

When both a URL as Intent.EXTRA_TEXT and a screenshot as Intent.EXTRA_STREAM
present, most apps favor the latter.
So we need to use a new extra name for a screenshot so that a URL could be
prioritized as it is.

BUG=455996
Committed: https://crrev.com/25e43a11186a1500420f772da4e08e2e926a9454
Cr-Commit-Position: refs/heads/master@{#324121}

[Jaekyun Seok (inactive), 2015-04-07 06:17:32]

jaekyun@chromium.org changed reviewers:
+ aurimas@chromium.org, tedchoc@chromium.org

[Jaekyun Seok (inactive), 2015-04-07 06:17:32]

Please review this CL.

[Ted C, 2015-04-07 17:33:26]

lgtm

[Jaekyun Seok (inactive), 2015-04-07 20:42:53]

The CQ bit was checked by jaekyun@chromium.org

[commit-bot: I haz the power, 2015-04-07 20:43:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1060243002/1

[commit-bot: I haz the power, 2015-04-07 21:15:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-07 21:16:34]

Patchset 1 (id:??) landed as
https://crrev.com/25e43a11186a1500420f772da4e08e2e926a9454
Cr-Commit-Position: refs/heads/master@{#324121}