tree e133a88e4c8c16d95bcac5df4df48bd1e8973a47
parent 59759043f66de17140b423a7f11a2d8827b4cbbf
author Michael Bolin <mbolin@fb.com> 1383790054 -0800
committer Michael Bolin <mbolin@fb.com> 1384307575 -0800

Introduce DexJavaLibraryIfItContainsClassFiles Buildable.

Summary:
`DexJavaLibraryIfItContainsClassFiles` is a `Buildable` that takes the output of a `JavaLibraryRule` and
and dexes it, assuming the output of the `JavaLibraryRule` contains `.class` files.
It relies on an `AccumulateClassNames` to determine whether there are `.class` files to dex.

Once `DexJavaLibraryIfItContainsClassFiles` has the path to the classes file,
it uses a `FileExistsAndIsNotEmptyStep` combined with a `ConditionalStep` to
make sure that the list of `.class` files is non-empty before running the `DxStep`
because `dx` will fail if it is run on input that does not contain any `.class` files.

Test Plan: Sandcastle builds.