Add contents property to boot_image (and prebuilt_boot_image)

Allows boot_image modules to be created for any module that contributes
to the boot class path, e.g. core-i18n from the com.android.i18n.

A boot_image module with a contents property cannot specify an
image_name, and vice versa. Only those boot_image modules with an
image_name create .art, .oat and .vdex files, either in their
associated APEX or as part of the framework "boot" image.

Bug: 177892522
Test: m nothing
Change-Id: Idfc2bcf00dd6d3ed36ac4df46fcf18e8aa7e2c92
diff --git a/java/boot_image_test.go b/java/boot_image_test.go
index a289df8..e1866de 100644
--- a/java/boot_image_test.go
+++ b/java/boot_image_test.go
@@ -101,3 +101,27 @@
 			}
 		`)
 }
+
+func TestBootImageWithoutImageNameOrContents(t *testing.T) {
+	prepareForTestWithBootImage.
+		ExtendWithErrorHandler(android.FixtureExpectsAtLeastOneErrorMatchingPattern(
+			`\Qneither of the "image_name" and "contents" properties\E`)).
+		RunTestWithBp(t, `
+			boot_image {
+				name: "boot-image",
+			}
+		`)
+}
+
+func TestBootImageWithImageNameAndContents(t *testing.T) {
+	prepareForTestWithBootImage.
+		ExtendWithErrorHandler(android.FixtureExpectsAtLeastOneErrorMatchingPattern(
+			`\Qboth of the "image_name" and "contents" properties\E`)).
+		RunTestWithBp(t, `
+			boot_image {
+				name: "boot-image",
+				image_name: "boot",
+				contents: ["other"],
+			}
+		`)
+}