Add a service-unique ID to BufferNode

All the BufferNode allocated by bufferhub hwservice now will have a
unique ID generated and managed by the UniqueIdGenerator.

The idGenerator is placed in global static namespace because 1)
therefore it is process-unique 2) BufferNode could still access it
without a reference to the service instance.

Added UniqueIdGenerator_test.

Test: UniqueIdGenerator_test, BufferNode_test, buffer_hub-test,
BufferHubBuffer_test passed.
Fix: 118844348
Change-Id: I9c9adebab3af7b9de71dbe8728d3f24ed231338d
diff --git a/services/bufferhub/tests/Android.bp b/services/bufferhub/tests/Android.bp
index cef31f6..8a30ef5 100644
--- a/services/bufferhub/tests/Android.bp
+++ b/services/bufferhub/tests/Android.bp
@@ -21,4 +21,20 @@
     ],
     // TODO(b/117568153): Temporarily opt out using libcrt.
     no_libcrt: true,
+}
+
+cc_test {
+    name: "UniqueIdGenerator_test",
+    srcs: ["UniqueIdGenerator_test.cpp"],
+    cflags: [
+        "-DLOG_TAG=\"UniqueIdGenerator_test\"",
+        "-DTRACE=0",
+        "-DATRACE_TAG=ATRACE_TAG_GRAPHICS",
+    ],
+    shared_libs: [
+        "libbufferhubservice",
+    ],
+    static_libs: [
+        "libgmock",
+    ],
 }
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