[fsp] Rename ObserveEntry with AddWatcher.

[fsp] Rename ObserveEntry with AddWatcher.

Since we may have more than one watcher, the previous naming didn't make sense.
This patch changes all naming related to observing entries into creating
watchers.

TEST=Refactoring only. All current tests should pass.
BUG=261491
Committed: https://crrev.com/39aaa52bf7843ecd64aad7faf5f0cfc5783bf161
Cr-Commit-Position: refs/heads/master@{#301596}

[mtomasz, 2014-10-27 06:45:18]

mtomasz@chromium.org changed reviewers:
+ fukino@chromium.org

[mtomasz, 2014-10-27 06:45:32]

mtomasz@chromium.org changed reviewers:
+ benwells@chromium.org

[mtomasz, 2014-10-27 06:46:07]

@benwells: PTAL at IDL.
@fukino: PTAL at the rest.

It's a pretty much mechanical renaming CL.

Thanks.

[fukino, 2014-10-27 10:29:36]

On 2014/10/27 06:46:07, mtomasz wrote:
> @benwells: PTAL at IDL.
> @fukino: PTAL at the rest.
> 
> It's a pretty much mechanical renaming CL.
> 
> Thanks.

lgtm.
Looks nice renaming to me, thanks!

[benwells, 2014-10-27 21:10:09]

lgtm

[mtomasz, 2014-10-28 08:11:03]

The CQ bit was checked by mtomasz@chromium.org

[commit-bot: I haz the power, 2014-10-28 08:12:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/674413002/20001

[commit-bot: I haz the power, 2014-10-28 11:53:00]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-10-28 11:54:01]

Patchset 2 (id:??) landed as
https://crrev.com/39aaa52bf7843ecd64aad7faf5f0cfc5783bf161
Cr-Commit-Position: refs/heads/master@{#301596}