media: Add ProvisionFetcher mojo interface and implementation.

media/mojo/services/BUILD.gn

Index: media/mojo/services/BUILD.gn
diff --git a/media/mojo/services/BUILD.gn b/media/mojo/services/BUILD.gn
index 8a6261f90850ffc04abcf6e5ed33a2ed858c6d42..24fcdfc44c8ea0acfd8b6208f9c1ed1e64f121c8 100644
--- a/media/mojo/services/BUILD.gn
+++ b/media/mojo/services/BUILD.gn
@@ -121,6 +121,13 @@ source_set("cdm_service") {
     "mojo_type_trait.h",
   ]
 
+  if (is_android) {
+    sources += [
+      "mojo_provision_fetcher.cc",
+      "mojo_provision_fetcher.h",
+    ]
+  }
+
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 }