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..e9f4443177963cb22410deb77cc47b6e2a81c7cb 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",
@@ -624,6 +624,11 @@ test("media_unittests") {
     "cdm/external_clear_key_test_helper.cc",
     "cdm/external_clear_key_test_helper.h",
     "cdm/json_web_key_unittest.cc",
+    "cdm/simple_cdm_allocator.cc",
+    "cdm/simple_cdm_allocator.h",
+    "cdm/simple_cdm_allocator_unittest.cc",
+    "cdm/simple_cdm_buffer.cc",
+    "cdm/simple_cdm_buffer.h",
     "filters/audio_clock_unittest.cc",
     "filters/audio_decoder_selector_unittest.cc",
     "filters/audio_renderer_algorithm_unittest.cc",