ApplicationManager: Use callback to get notified on application shutdown.

ApplicationManager: Use callback to get notified on application shutdown.

Until now, the Delegate had a OnApplicationError that was called
whenever an application ended. Because it was used to keep track of when
a given started application ended, it needed to send back the URL that
was used to start an application. This was cumbersome as mapping and
rediect change the url during the loading process.

Instead this change allows a caller fo ApplicationManager to register a
closure that will be called when the application ends, if the call
started a new application.

R=davemoore@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/993869e76244efcbeeb4c6fa37cb52835115ef36

[DaveMoore, 2015-03-06 17:34:43]

I like the approach but please add a test.

[qsr, 2015-03-09 16:50:21]

Added test.

https://codereview.chromium.org/983113002/diff/1/shell/application_manager/ap...
File shell/application_manager/application_manager.cc (right):

https://codereview.chromium.org/983113002/diff/1/shell/application_manager/ap...
shell/application_manager/application_manager.cc:207:
shell->InitializeApplication(GetArgsForURL(app_url));
I cannot push this until this is fixed -> this changed the behavior from using
the requested url to using the app url.

Using the requested url seems bad to me (because the app won't receive the same
arguments depending on which URL is used the first time it is connected to), but
using the real app url is not very good either because it will now be depending
on all the mapping, and redirect, some that cannot be known in advance.

I'm proposing the following, that I will implement in another CL if that's fine
with you:

If an URL A is mapped to B, and that both A and B have arguments, we should
concatenate all arguments and pass it to the app whether it is called with URL A
or B.

Now, we still have an issue with http redirect. Unfortunately I do not have a
very good solution, and I propose we continue to send the arguments that can be
found by using the given URL, it means that if an URL A is mapped to B, it will
not get the same arguments whether it is called the first time with A, or
directly with B.

 We kind of need this, because when we will map URL to the cloud to get the last
version of the app, we will still want to pass argument using the canonical name
for those Apps.

 WDYT?

[qsr, 2015-03-10 14:46:11]

gentle ping?

[DaveMoore, 2015-03-10 17:26:50]

lgtm

[qsr, 2015-03-24 12:35:32]

Committed patchset #4 (id:60001) manually as
993869e76244efcbeeb4c6fa37cb52835115ef36 (presubmit successful).