Add exported_bootclasspath_fragments to prebuilt_apex/apex_set

This is needed to allow a prebuilt_bootclasspath_fragment to be used
interchangeably with a bootclasspath_fragment in the
platform_bootclasspath module.

The platform_bootclasspath module depends on APEX specific variants of
bootclasspath_fragment modules. That works because the
bootclasspath_fragment modules are part of an apex and so have an APEX
specific variant which the platform_bootclasspath can specify.

Using a prebuilt_bootclasspath_fragment in place of a
bootclasspath_fragment requires that the prebuilt also has an APEX
specific variant.

Specifying exported_bootclasspath_fragments on a prebuilt_apex/apex_set
will cause it to create an APEX variant for the named module whcih will
allow it to be selected by the platform_bootclasspath module.

Bug: 186034565
Bug: 177892522
Test: m nothing
Change-Id: I7ddacc6498ec3a4a9f26c5f78b7f9a033e494d78

sdk/bootclasspath_fragment_sdk_test.go

@@ -24,6 +24,7 @@ import (
 func TestSnapshotWithBootclasspathFragment_ImageName(t *testing.T) {
 	result := android.GroupFixturePreparers(
 		prepareForSdkTestWithJava,
+		java.PrepareForTestWithJavaDefaultModules,
 		prepareForSdkTestWithApex,
 
 		// Some additional files needed for the art apex.
@@ -32,6 +33,20 @@ func TestSnapshotWithBootclasspathFragment_ImageName(t *testing.T) {
 			"com.android.art.pem":                                nil,
 			"system/sepolicy/apex/com.android.art-file_contexts": nil,
 		}),
+
+		// platform_bootclasspath that depends on the fragment.
+		android.FixtureAddTextFile("frameworks/base/boot/Android.bp", `
+			platform_bootclasspath {
+				name: "platform-bootclasspath",
+				fragments: [
+					{
+						apex: "com.android.art",
+						module: "mybootclasspathfragment",
+					},
+				],
+			}
+		`),
+
 		java.FixtureConfigureBootJars("com.android.art:mybootlib"),
 		android.FixtureWithRootAndroidBp(`
 			sdk {
@@ -72,6 +87,23 @@ func TestSnapshotWithBootclasspathFragment_ImageName(t *testing.T) {
 		`),
 	).RunTest(t)
 
+	// A preparer to add a prebuilt apex to the test fixture.
+	prepareWithPrebuiltApex := android.GroupFixturePreparers(
+		android.FixtureAddTextFile("prebuilts/apex/Android.bp", `
+				prebuilt_apex {
+					name: "com.android.art",
+					src: "art.apex",
+					exported_java_libs: [
+						"mybootlib",
+					],
+					exported_bootclasspath_fragments: [
+						"mybootclasspathfragment",
+					],
+				}
+			`),
+		android.FixtureAddFile("prebuilts/apex/art.apex", nil),
+	)
+
 	CheckSnapshot(t, result, "mysdk", "",
 		checkUnversionedAndroidBpContents(`
 // This is auto-generated. DO NOT EDIT.
@@ -121,19 +153,9 @@ sdk_snapshot {
 		checkAllCopyRules(`
 .intermediates/mybootlib/android_common/javac/mybootlib.jar -> java/mybootlib.jar
 `),
-		snapshotTestPreparer(checkSnapshotPreferredWithSource, android.GroupFixturePreparers(
-			android.FixtureAddTextFile("prebuilts/apex/Android.bp", `
-				prebuilt_apex {
-					name: "com.android.art",
-					src: "art.apex",
-					exported_java_libs: [
-						"mybootlib",
-					],
-				}
-			`),
-			android.FixtureAddFile("prebuilts/apex/art.apex", nil),
-		),
-		),
+		snapshotTestPreparer(checkSnapshotWithoutSource, prepareWithPrebuiltApex),
+		snapshotTestPreparer(checkSnapshotWithSourcePreferred, prepareWithPrebuiltApex),
+		snapshotTestPreparer(checkSnapshotPreferredWithSource, prepareWithPrebuiltApex),
 	)
 }