ART: Add GC callbacks

Add start and end of pause callbacks.

Fix setup and missing functions in test 907.

Bug: 31684633
Test: m test-art-host
Test: m test-art-host-run-test-908-gc-start-finish
Change-Id: I1d8872ef9cd6914de7fb033cd873f8d5cb48ea17
diff --git a/test/907-get-loaded-classes/get_loaded_classes.cc b/test/907-get-loaded-classes/get_loaded_classes.cc
index e752bcb..9ceefcb 100644
--- a/test/907-get-loaded-classes/get_loaded_classes.cc
+++ b/test/907-get-loaded-classes/get_loaded_classes.cc
@@ -77,5 +77,16 @@
   return ret;
 }
 
+// Don't do anything
+jint OnLoad(JavaVM* vm,
+            char* options ATTRIBUTE_UNUSED,
+            void* reserved ATTRIBUTE_UNUSED) {
+  if (vm->GetEnv(reinterpret_cast<void**>(&jvmti_env), JVMTI_VERSION_1_0)) {
+    printf("Unable to get jvmti env!\n");
+    return 1;
+  }
+  return 0;
+}
+
 }  // namespace Test907GetLoadedClasses
 }  // namespace art
diff --git a/test/907-get-loaded-classes/run b/test/907-get-loaded-classes/run
index 3e135a3..3f5a059 100755
--- a/test/907-get-loaded-classes/run
+++ b/test/907-get-loaded-classes/run
@@ -37,7 +37,7 @@
 
 ./default-run "$@" --experimental agents \
                    --experimental runtime-plugins \
-                   --runtime-option -agentpath:${agent}=906-iterate-heap,${arg} \
+                   --runtime-option -agentpath:${agent}=907-get-loaded-classes,${arg} \
                    --android-runtime-option -Xplugin:${plugin} \
                    ${other_args} \
                    --args ${lib}