Spatializer: Add rate based stats

A new class ThreadSnapshot encapsulates
current (and future) thread based statistics.

Test: adb shell dumpsys media.audio_flinger --all
Test: atest media_threadsnapshot_tests
Bug: 228648325
Change-Id: Idbfdee08032c56f2c47e2e48d2ceb0656168c125
diff --git a/media/utils/tests/Android.bp b/media/utils/tests/Android.bp
index d9c2b21..a6f408d 100644
--- a/media/utils/tests/Android.bp
+++ b/media/utils/tests/Android.bp
@@ -104,6 +104,26 @@
 }
 
 cc_test {
+    name: "media_threadsnapshot_tests",
+
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wextra",
+    ],
+
+    shared_libs: [
+        "liblog",
+        "libmediautils",
+        "libutils",
+    ],
+
+    srcs: [
+        "media_threadsnapshot_tests.cpp",
+    ],
+}
+
+cc_test {
     name: "methodstatistics_tests",
 
     cflags: [