None of these operating systems are fuchsia

None of these operating systems are fuchsia

This CL lets common dependencies between Chromium and Fuchsia build with the
same set of BUILD.gn files. For example, Skia can now check is_fuchsia in their
BUILD.gn file to configure their build for Fuchsia.

This patch will also be useful when if/when we port Chromium to Fuchsia.

R=brettw@chromium.org

[abarth, 2016-07-15 17:24:08]

abarth@google.com changed reviewers:
+ abarth@google.com

[brettw, 2016-07-15 20:06:37]

Given the uncertainty here and the fact that most people don't even know what
this is, I would prefer not to land this now.

These booleans are there just to make the syntax a bit harder to mess up and
allow overlaps (posix, linux apply to multiple things). The overlaps at least
don't apply to you.

For now, if you want build files to check this, they can always check
  if (current_os == "fuscia") { ... }
We already do this for some variants of WindowsRT, for example (open source
people have contributed this), and WindowsRT seems more real that Fuscia at this
point.

If/when this is a supported thing and our build files start doing this
comparison more often, we can promote this to be a global flag for all build
variants.

[abarth, 2016-07-18 21:48:26]

On 2016/07/15 at 20:06:37, brettw wrote:
> For now, if you want build files to check this, they can always check
>   if (current_os == "fuscia") { ... }
> We already do this for some variants of WindowsRT, for example (open source
people have contributed this),

Ok, we can use that workaround for now.  It's less good than having the gn
variable because gn provides error checking for variables (e.g., for typos). 
Certainly in our own BUILDCONFIG.gn we use a variable here for this reason. 
It's unfortunate that our shared dependencies (e.g., Skia) will have more
error-prone BUILD.gn files than they would if our projects were more willing to
cooperate on these trivial things.

> WindowsRT seems more real that Fuscia at this point.

I'm not sure what point you were trying to make with this statement, but it
seems pretty rude to characterize the work my team is doing as not real.  :(

[brettw, 2016-07-20 19:23:23]

On 2016/07/18 21:48:26, abarth wrote:
> On 2016/07/15 at 20:06:37, brettw wrote:
> > For now, if you want build files to check this, they can always check
> >   if (current_os == "fuscia") { ... }
> > We already do this for some variants of WindowsRT, for example (open source
> people have contributed this),
> 
> Ok, we can use that workaround for now.  It's less good than having the gn
> variable because gn provides error checking for variables (e.g., for typos). 
> Certainly in our own BUILDCONFIG.gn we use a variable here for this reason. 
> It's unfortunate that our shared dependencies (e.g., Skia) will have more
> error-prone BUILD.gn files than they would if our projects were more willing
to
> cooperate on these trivial things.
> 
> > WindowsRT seems more real that Fuscia at this point.
> 
> I'm not sure what point you were trying to make with this statement, but it
> seems pretty rude to characterize the work my team is doing as not real.  :(

I am trying to say we've rejected similar use cases that already have more code
landed in the Chrome repo. The intent is not to provide a global build variable
for everything anybody thinks of doing. The string is deliberately design to
allow these more experimental enhancements.