Add listener callback to keep track of tracing state in SCC

Test: N/A
Change-Id: Iae1fe69b65a449f7e94fecaa17081022b0888c7b
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index e860dff..4b91da8 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -4885,6 +4885,7 @@
             }
             return OK;
         }
+        case ADD_TRANSACTION_TRACE_LISTENER:
         case CAPTURE_DISPLAY_BY_ID: {
             IPCThreadState* ipc = IPCThreadState::self();
             const int uid = ipc->getCallingUid();
@@ -6230,6 +6231,17 @@
     }));
 }
 
+status_t SurfaceFlinger::addTransactionTraceListener(
+        const sp<gui::ITransactionTraceListener>& listener) {
+    if (!listener) {
+        return BAD_VALUE;
+    }
+
+    mInterceptor->addTransactionTraceListener(listener);
+
+    return NO_ERROR;
+}
+
 } // namespace android
 
 #if defined(__gl_h_)