Add allocator interface for use by cdm_adapter

media/BUILD.gn

Index: media/BUILD.gn
diff --git a/media/BUILD.gn b/media/BUILD.gn
index f22d585106b46909f6fb311c3890d67d980d4796..dbb5f07d0b65c0850a00a57e75e475e157b26559 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -174,8 +174,8 @@ component("media") {
     "cdm/aes_decryptor.h",
     "cdm/cdm_adapter.cc",
     "cdm/cdm_adapter.h",
-    "cdm/cdm_buffer_impl.cc",
-    "cdm/cdm_buffer_impl.h",
+    "cdm/cdm_allocator.cc",
+    "cdm/cdm_allocator.h",
     "cdm/cdm_helpers.cc",
     "cdm/cdm_helpers.h",
     "cdm/default_cdm_factory.cc",
@@ -188,6 +188,10 @@ component("media") {
     "cdm/player_tracker_impl.h",
     "cdm/proxy_decryptor.cc",
     "cdm/proxy_decryptor.h",
+    "cdm/simple_cdm_allocator.cc",
+    "cdm/simple_cdm_allocator.h",
+    "cdm/simple_cdm_buffer.cc",
+    "cdm/simple_cdm_buffer.h",
     "cdm/supported_cdm_versions.cc",
     "cdm/supported_cdm_versions.h",
     "ffmpeg/ffmpeg_deleters.h",