aaudio: fix some state transitions

Now requestStop() and requestPause() do the appropriate thing
based on state.
Flush is allowed when OPEN, PAUSED or STOPPED because there might
be pre-roll data.

Bug: 69810494
Test: test_various.cpp
Change-Id: Ie1b306b17734a58fa71b1742bb186482893656b7
diff --git a/media/libaaudio/src/client/AudioStreamInternalPlay.h b/media/libaaudio/src/client/AudioStreamInternalPlay.h
index d5c1b1e..04e4a62 100644
--- a/media/libaaudio/src/client/AudioStreamInternalPlay.h
+++ b/media/libaaudio/src/client/AudioStreamInternalPlay.h
@@ -37,6 +37,16 @@
 
     aaudio_result_t requestFlush() override;
 
+    bool isFlushSupported() const override {
+        // Only implement FLUSH for OUTPUT streams.
+        return true;
+    }
+
+    bool isPauseSupported() const override {
+        // Only implement PAUSE for OUTPUT streams.
+        return true;
+    }
+
     aaudio_result_t write(const void *buffer,
                           int32_t numFrames,
                           int64_t timeoutNanoseconds) override;
@@ -52,8 +62,6 @@
 
 protected:
 
-    aaudio_result_t requestPauseInternal();
-
     void advanceClientToMatchServerPosition() override;
 
     void onFlushFromServer() override;