Effect AIDL Check visualizer latency parameter

Add default value for class members.
Update mutex locking for some members.

Bug: 258124419
Test: atest VtsHalVisualizerTargetTest
Change-Id: I98c9b7a488e1d6d910428eae7e9f4cb011deb13e
diff --git a/media/libeffects/visualizer/aidl/VisualizerContext.cpp b/media/libeffects/visualizer/aidl/VisualizerContext.cpp
index 35ebdfb..1965e0e 100644
--- a/media/libeffects/visualizer/aidl/VisualizerContext.cpp
+++ b/media/libeffects/visualizer/aidl/VisualizerContext.cpp
@@ -122,6 +122,11 @@
 }
 
 RetCode VisualizerContext::setDownstreamLatency(int latency) {
+    if (latency < 0 || (unsigned)latency > kMaxLatencyMs) {
+        LOG(ERROR) << __func__ << " latency " << latency << " exceed valid range: 0 - "
+                   << kMaxLatencyMs;
+        return RetCode::ERROR_ILLEGAL_PARAMETER;
+    }
     std::lock_guard lg(mMutex);
     mDownstreamLatency = latency;
     return RetCode::SUCCESS;