SF: Add a flag for the connected-display feature

Bug: 299486625
Test: adb shell dumpsys SurfaceFlinger  -- check for
"ConnectedDisplayFlagValue"

Change-Id: I4526091ca938ef378877edf63b499a3c8c8a39d9
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index a7f2845..517dc96 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -494,7 +494,9 @@
     mLegacyFrontEndEnabled = !mLayerLifecycleManagerEnabled ||
             base::GetBoolProperty("persist.debug.sf.enable_legacy_frontend"s, false);
 
+    // Trunk-Stable flags
     mMiscFlagValue = flags::misc1();
+    mConnectedDisplayFlagValue = flags::connected_display();
 }
 
 LatchUnsignaledConfig SurfaceFlinger::getLatchUnsignaledConfig() {
@@ -6342,6 +6344,8 @@
     colorizer.reset(result);
 
     StringAppendF(&result, "MiscFlagValue: %s\n", mMiscFlagValue ? "true" : "false");
+    StringAppendF(&result, "ConnectedDisplayFlagValue: %s\n",
+                  mConnectedDisplayFlagValue ? "true" : "false");
 
     getRenderEngine().dump(result);