Fixes metrics collection during CdmEngine close.

This fixes a problem where a CdmEngine instance (and its sessions) could
be closed before its metrics could be collected. The change allows the
wv_content_decryption_module to extract metrics from instances about to
be closed. These are held until reported to the caller.

Test: Manually verified that collection is now occurring correctly. Also
added unit test: wv_cdm_metric_test.

This is a merge from wvgerrit/29069

Change-Id: If82bfd5cae3b72b9d14ab4741424a7ae7cc0a3a6

libwvdrmengine/mediadrm/Android.mk

@@ -25,6 +25,9 @@ LOCAL_HEADER_LIBRARIES := \
 LOCAL_SHARED_LIBRARIES := \
   liblog
 
+LOCAL_STATIC_LIBRARIES := \
+  libcdm_protos
+
 LOCAL_MODULE := libwvdrmdrmplugin
 LOCAL_PROPRIETARY_MODULE := true
 
@@ -56,7 +59,9 @@ LOCAL_C_INCLUDES := \
 LOCAL_HEADER_LIBRARIES := \
   libutils_headers \
 
-LOCAL_STATIC_LIBRARIES := libcrypto_static
+LOCAL_STATIC_LIBRARIES := \
+  libcdm_protos \
+  libcrypto_static
 
 LOCAL_SHARED_LIBRARIES := \
   android.hardware.drm@1.0 \