Extract CdmManager from MojoCdmService.

media/BUILD.gn

Index: media/BUILD.gn
diff --git a/media/BUILD.gn b/media/BUILD.gn
index 1e5cebcefd2194cb884b27491ad9db58ca99a15b..7d1389435fd87331933789533f7bea6ed918b29f 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -511,6 +511,31 @@ component("media") {
   }
 }
 
+config("cdm_manager_implementation") {
+  defines = [ "CDM_MANAGER_IMPLEMENTATION" ]
+}
+
+# cdm_manager must not be a source_set() because CdmManager exposes a static
+# singleton, shared by multiple component()s.
+#
+# TODO(xhwang): Remove this component once AVDA no longer depends on it.
+component("cdm_manager") {
+  visibility = [
+    "//media/gpu",
+    "//media/mojo/services:lib",
+  ]
+  sources = [
+    "cdm/cdm_manager.cc",
+    "cdm/cdm_manager.h",
+    "cdm/cdm_manager_export.h",
+  ]
+  configs += [ ":cdm_manager_implementation" ]
+  deps = [
+    ":media",
+    "//base",
+  ]
+}
+
 static_library("cdm_paths") {
   sources = [
     "cdm/cdm_paths.cc",