Move session_id.{cc,h} from chrome/browser/sessions to components/sessions

Move session_id.{cc,h} from chrome/browser/sessions to components/sessions

Move SessionID out of chrome/ to make it usable from non-Chrome embedders like app_shell and athena.

Move methods IdForTab() and IdForWindowContainingTab() from SessionID to SessionTabHelper to make SessionID chrome-free.
Move SessionID to components/sessions.
Fix gyp, BUILD.gn and DEPS.

BUG=403726
TBR=sky@chromium.org for include fix under chrome/browser

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=290242

[hashimoto, 2014-08-18 08:07:06]

Please review.
This patch should not introduce any behavior change.

[marja, 2014-08-18 08:11:11]

hmm... so after this patch SessionID is just a wrapper around int32? Does it
make sense to have a separate class for it?

[hashimoto, 2014-08-18 08:16:56]

On 2014/08/18 08:11:11, marja wrote:
> hmm... so after this patch SessionID is just a wrapper around int32? Does it
> make sense to have a separate class for it?

IIUC the main role of SessionID is to increment its static integer member
variable to generate a unique number whenever a SessionID instance is created.
Do you think this doesn't justify us to maintain a separate class?

[marja, 2014-08-18 08:21:29]

On 2014/08/18 08:16:56, hashimoto wrote:
> On 2014/08/18 08:11:11, marja wrote:
> > hmm... so after this patch SessionID is just a wrapper around int32? Does it
> > make sense to have a separate class for it?
> 
> IIUC the main role of SessionID is to increment its static integer member
> variable to generate a unique number whenever a SessionID instance is created.
> Do you think this doesn't justify us to maintain a separate class?

One alternative could be to move that functionality to SessionTabHelper, since
all the other non-trivial functions are moved there too. But I'm not sure if
that + not having the SessionID a better option than this CL.. maybe not.

So, LGTM for this approach. If we'd like to get rid of SessionID, we should
consult sky@ too...

[hashimoto, 2014-08-18 09:44:13]

TBRing sky@chromium.org for include fix under chrome/browser

[hashimoto, 2014-08-18 10:00:28]

The CQ bit was checked by hashimoto@chromium.org

[commit-bot: I haz the power, 2014-08-18 10:01:14]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/hashimoto@chromium.org/480883002/20001

[commit-bot: I haz the power, 2014-08-18 12:42:19]

Committed patchset #1 (20001) as 290242