Shell: Make a separate binary for child processes.

Shell: Make separate binary for child processes.

To do (separately): Slim down the deps for the child process.

For comparison, on an Android Debug build, the stripped binary for the main process is ~2.4 MB whereas the child is ~850 kB (as seen in MojoShell.apk).

R=davemoore@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/e0a4a1866c09a92d34539c652e0301fcb70c65c6

[viettrungluu, 2015-04-07 21:32:28]

viettrungluu@chromium.org changed reviewers:
+ davemoore@chromium.org

[DaveMoore, 2015-04-07 22:27:30]

https://codereview.chromium.org/1061413002/diff/40001/shell/child_main.cc
File shell/child_main.cc (right):

https://codereview.chromium.org/1061413002/diff/40001/shell/child_main.cc#new...
shell/child_main.cc:291: switches::kChildProcess));
this seems unnecessary. Why bother with having a switch?

https://codereview.chromium.org/1061413002/diff/40001/shell/desktop/main.cc
File shell/desktop/main.cc (right):

https://codereview.chromium.org/1061413002/diff/40001/shell/desktop/main.cc#n...
shell/desktop/main.cc:115:
CHECK(!command_line.HasSwitch(switches::kChildProcess));
Seems like we can drop this too. If you're running the wrong shell / child it's
your own damn fault.

[viettrungluu, 2015-04-07 22:35:25]

On 2015/04/07 22:27:30, DaveMoore wrote:
> https://codereview.chromium.org/1061413002/diff/40001/shell/child_main.cc
> File shell/child_main.cc (right):
> 
>
https://codereview.chromium.org/1061413002/diff/40001/shell/child_main.cc#new...
> shell/child_main.cc:291: switches::kChildProcess));
> this seems unnecessary. Why bother with having a switch?

Mostly to prevent accidental confusion, to make sure that no one accidentally
runs it and expects something sensible, and to intentionally blow up in an
obvious way. (If I were nicer, I'd include a helpful error message.)

Also, since we go through some contortions to figure out what binary to run (and
these contortions differ between Linux and Android), it's nice to make sure we
don't accidentally invoke the wrong binary.

> 
> https://codereview.chromium.org/1061413002/diff/40001/shell/desktop/main.cc
> File shell/desktop/main.cc (right):
> 
>
https://codereview.chromium.org/1061413002/diff/40001/shell/desktop/main.cc#n...
> shell/desktop/main.cc:115:
> CHECK(!command_line.HasSwitch(switches::kChildProcess));
> Seems like we can drop this too. If you're running the wrong shell / child
it's
> your own damn fault.

[DaveMoore, 2015-04-07 23:13:33]

lgtm

[viettrungluu, 2015-04-07 23:28:06]

Committed patchset #4 (id:60001) manually as
e0a4a1866c09a92d34539c652e0301fcb70c65c6 (presubmit successful).

[qsr, 2015-04-08 09:27:43]

qsr@chromium.org changed reviewers:
+ qsr@chromium.org

[qsr, 2015-04-08 09:27:44]

https://codereview.chromium.org/1061413002/diff/60001/shell/android/apk/src/o...
File shell/android/apk/src/org/chromium/mojo/shell/ShellMain.java (right):

https://codereview.chromium.org/1061413002/diff/60001/shell/android/apk/src/o...
shell/android/apk/src/org/chromium/mojo/shell/ShellMain.java:30: // Not really
an executable, but what we'll use for "argv[0]" (along with the path).
It is an executable. android executable are pie, which mean they can be used as
shared libraries. Now, if we do not execute it anymore, we do not need to set it
to argv[0] anymore.

https://codereview.chromium.org/1061413002/diff/60001/shell/android/main.cc
File shell/android/main.cc (right):

https://codereview.chromium.org/1061413002/diff/60001/shell/android/main.cc#n...
shell/android/main.cc:230: // TODO(vtl): We need a main(), even though it should
never be called.
If we do not need to run this anymore, I'll need to redefine this as a
shared_library instead of an executable, and we won't need this main anymore.