Move components/native_app_window to extensions/components/native_app_window

There's currently a dependency cycle between gyp files: components.gyp
and extensions.gyp. extensions.gyp depends on a number of components,
and two components depend on exetensions.gyp. These are:
 - components/renderer_context_menu/
 - components/native_app_window/ (more recently)

renderer_context_menu has an "optional" extensions dependency, which can
be skipped when ENABLE_EXTENSIONS is not defined. Still, it is necessary
for renderer_context_menu.gyp to omit its extensions.gyp dependency and
build as a static library.

For native_app_window, since it is not compiled on Mac, the gyp circular
check is not performed on the bots.

This CL fixes the layering by adding a folder,
src/extensions/components. Things here may depend on extensions, but not
on other extensions/components folders in a way that creates a cycle.
This also allows the benefits of a component-architecture to make sense
of interdependencies between the ~1337 files under src/extensions.

This layout also makes it clear that by depending on one of these
components, a target is also depending on src/extensions. Currently,
this is not clear.

BUG=35878, 418455
TBR=reed@google.com

Review URL: https://codereview.chromium.org/606953002

Cr-Commit-Position: refs/heads/master@{#297952}
29 files changed