Revert "Revert "audioflinger: implement silenced capture for mmap""

This reverts commit 611ebb95e76c230214780b7b583b8a3c5277ac7a.

Bug: 78118584
bug: 72134552
Test: 'adb shell write_sine_callback -m3 -pl -s100 -x' and Plug headphones in and out.
Test: AAudio CTS tests
Change-Id: I7558ad7b9c6c2d352ebce105382fe914c26fd35e
diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index 3fe41d8..aff1239 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -1946,7 +1946,7 @@
                   sessionId, uid, false /* isOut */,
                   ALLOC_NONE,
                   TYPE_DEFAULT, portId),
-        mPid(pid)
+        mPid(pid), mSilenced(false), mSilencedNotified(false)
 {
 }