Add bootclasspath_fragment.

Note that the contents of the bootclasspath_fragment are added as
dependencies to an apex, so there is no need to duplicate them in
java_libs.

Bug: 180105615
Test: atest CtsClasspathsTestCases
Change-Id: I1537d8a30c67995955af2d2d1bb2c11f01a24fe9
diff --git a/apex/Android.bp b/apex/Android.bp
index 6c45749..d911ad3 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -24,8 +24,8 @@
 apex_defaults {
     name: "com.android.media-defaults",
     updatable: true,
+    bootclasspath_fragments: ["com.android.media-bootclasspath-fragment"],
     java_libs: [
-      "updatable-media",
       "service-media-s",
     ],
     multilib: {
@@ -94,6 +94,13 @@
     installable: false,
 }
 
+// Encapsulate the contributions made by the com.android.media to the bootclasspath.
+bootclasspath_fragment {
+    name: "com.android.media-bootclasspath-fragment",
+    contents: ["updatable-media"],
+    apex_available: ["com.android.media"],
+}
+
 filegroup {
     name: "com.android.media-androidManifest",
     srcs: ["AndroidManifest-media.xml"],