Refactor GuestViewContainer::AttachRequest to allow for other request types

Refactor GuestViewContainer::AttachRequest to allow for other request types

In a subsequent CL, DetachGuest will be introduced, to allow a GuestView to
detach itself from its container. This CL performs the necessary refactor to allow
for new operations to be easily introduced.

This CL also makes BrowserPlugin IDs unique per process. This allows addressing attachment, and soon detachment, across JavaScript contexts.

BUG=434226
TBR=lazyboy@chromium.org

Committed: https://crrev.com/d397750f3e2e53f414a4798c4e5039837a8c00ea
Cr-Commit-Position: refs/heads/master@{#306025}

Committed: https://crrev.com/d0ff598d6d604ba3ac0cc940c27d5898c2640658
Cr-Commit-Position: refs/heads/master@{#306101}

[Fady Samuel, 2014-11-27 18:14:37]

fsamuel@chromium.org changed reviewers:
+ paulmeyer@chromium.org

[paulmeyer, 2014-11-27 18:50:27]

lgtm

[Fady Samuel, 2014-11-27 19:15:14]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2014-11-27 19:15:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/765843003/20001

[commit-bot: I haz the power, 2014-11-27 19:15:49]

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

[commit-bot: I haz the power, 2014-11-27 19:15:50]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Fady Samuel, 2014-11-27 19:20:30]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2014-11-27 19:20:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/765843003/20001

[commit-bot: I haz the power, 2014-11-27 20:21:07]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-11-27 20:21:45]

Patchset 2 (id:??) landed as
https://crrev.com/d397750f3e2e53f414a4798c4e5039837a8c00ea
Cr-Commit-Position: refs/heads/master@{#306025}

[danakj, 2014-11-28 03:31:44]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/764863003/ by danakj@chromium.org.

The reason for reverting is: Bots appear to be complaining of static
initializers.
http://build.chromium.org/p/chromium/buildstatus?builder=Linux&number=55741.

[Fady Samuel, 2014-11-28 16:40:24]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2014-11-28 16:41:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/765843003/40001

[commit-bot: I haz the power, 2014-11-28 17:53:20]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2014-11-28 17:54:03]

Patchset 3 (id:??) landed as
https://crrev.com/d0ff598d6d604ba3ac0cc940c27d5898c2640658
Cr-Commit-Position: refs/heads/master@{#306101}