viz: Move some code into //components/viz/common.

components/viz/host/gpu/DEPS

Index: components/viz/host/gpu/DEPS
diff --git a/components/viz/host/gpu/DEPS b/components/viz/host/gpu/DEPS
new file mode 100644
index 0000000000000000000000000000000000000000..9b455745a44b27f2d2f453dfb003a5dc0d52a7e0
--- /dev/null
+++ b/components/viz/host/gpu/DEPS
@@ -0,0 +1,3 @@
+include_rules = [
+  "+services/ui/gpu/interfaces",

[danakj, 2017/06/14 21:34:06]

Is it weird to dep from components to services? Can you convince me this isn't
weird, and we don't need to do dependency injection instead?

[Fady Samuel, 2017/06/14 21:35:23]

I think the interface should just move here...

[sadrul, 2017/06/14 21:40:59]

My opinion is that interfaces should remain under //services/. One of the
reasons we are moving code out of //services/ui/* into //components/viz is to
avoid introducing dependency on interface-implementation code in //services/
from //content. So it should be OK to leave just the interfaces in their place
under //services. This does not drag in additional dependency on impl code in
//services/, so this should be acceptable.

[danakj, 2017/06/14 21:52:08]

Ok thanks, so the rule would be .../interfaces is okay, but nothing else. A
comment here explaining this rule would be appreciated, and maybe up at a higher
level in c/viz/README.md so you can point me at that in the future :)

One more Q to verify, but what you said there makes sense to me: Do the
interfaces in this directory always exist? Would there be cases where we want to
use this component but not use these services interfaces? In content? In tests?
(Assume tests are happy making mojo interfaces in general.)

+]