DO NOT REVIEW Plumb push messaging registration through to gcm.

DO NOT REVIEW

Plumb push messaging registration through to gcm.

The Blink counterpart is 152763002.

Class diagrams:
https://www.lucidchart.com/documents/view/4336-0378-530494f3-9ce0-1a5e0a005ed1
https://www.lucidchart.com/documents/view/4ffc-b120-5305ebfa-9d0a-31410a005610

Intent to implement thread: 
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/GLXyXABvA_0 

BUG=350378

[Michael van Ouwerkerk, 2014-03-10 15:20:30]

Hi Jochen, this needs to be broken into smaller pieces, and tests. Could you
please take a look for the general perspective though? Thanks!

[jochen (gone - plz use gerrit), 2014-03-11 14:41:19]

On 2014/03/10 15:20:30, Michael van Ouwerkerk wrote:
> Hi Jochen, this needs to be broken into smaller pieces, and tests. Could you
> please take a look for the general perspective though? Thanks!

Hum, i'm not sure I understand the overall picture.

The idea is that the web site can register to receive push messages with these
classes, right?

But once registered, how will you receive those messages?

And what happens if a message arrives and I don't have the site open in a tab?

[Michael van Ouwerkerk, 2014-03-11 15:38:03]

On 2014/03/11 14:41:19, jochen wrote:
> On 2014/03/10 15:20:30, Michael van Ouwerkerk wrote:
> > Hi Jochen, this needs to be broken into smaller pieces, and tests. Could you
> > please take a look for the general perspective though? Thanks!
> 
> Hum, i'm not sure I understand the overall picture.
> 
> The idea is that the web site can register to receive push messages with these
> classes, right?
> 
> But once registered, how will you receive those messages?
> 
> And what happens if a message arrives and I don't have the site open in a tab?

Hi Jochen, you're right, this is just the registration part. We'll bring up a
Service Worker to fire a message event in it. The work for specifying this is
underway. Until then, think "event in Service Worker" wherever "System Message"
is mentioned here: https://dvcs.w3.org/hg/push/raw-file/tip/index.html

[jochen (gone - plz use gerrit), 2014-03-12 13:01:34]

ok, overall the direction looks good