aaudio: steal exclusive streams

An app (B) that asks for an exclusive stream can steal
an exclusive stream from an earlier app (A).
App B will be given the MMAP resource as a SHARED stream.
The stream for app A will be disconnected and released
by the service.
If app A reopens a stream then it will get a SHARED
stream.

The order of the opening of the streams is controlled by using a
recursive_mutex in AAudioService::openStream().

Bug: 129846760
Test: media/libaaudio/tests/test_steal_exclusive.cpp
Test: also
Test: Launch AudioTroubleMaker. It should say "EXCLUSIVE".
Test: Press Home button.
Test: Siren sound from AudioTroubleMaker should continue.
Test: Launch OboeTester
Test: TEST OUTPUT, then Open, Start
Test: You should get an MMAP SHARED stream on Pixel.
Test: Go back to AudioTroubleMaker. It should say "SHARED".
Change-Id: I7f8339d8ed62546520a9b46ed398418b41ca2832
diff --git a/services/oboeservice/AAudioEndpointManager.h b/services/oboeservice/AAudioEndpointManager.h
index ba17853..ae776b1 100644
--- a/services/oboeservice/AAudioEndpointManager.h
+++ b/services/oboeservice/AAudioEndpointManager.h
@@ -19,6 +19,7 @@
 
 #include <map>
 #include <mutex>
+#include <sys/types.h>
 #include <utils/Singleton.h>
 
 #include "binding/AAudioServiceMessage.h"
@@ -62,7 +63,8 @@
 
 private:
     android::sp<AAudioServiceEndpoint> openExclusiveEndpoint(android::AAudioService &aaudioService,
-                                                 const aaudio::AAudioStreamRequest &request);
+                                                 const aaudio::AAudioStreamRequest &request,
+                                                 sp<AAudioServiceEndpoint> &endpointToSteal);
 
     android::sp<AAudioServiceEndpoint> openSharedEndpoint(android::AAudioService &aaudioService,
                                               const aaudio::AAudioStreamRequest &request);
@@ -91,11 +93,16 @@
     int32_t mExclusiveFoundCount  = 0; // number of times we FOUND an exclusive endpoint
     int32_t mExclusiveOpenCount   = 0; // number of times we OPENED an exclusive endpoint
     int32_t mExclusiveCloseCount  = 0; // number of times we CLOSED an exclusive endpoint
+    int32_t mExclusiveStolenCount = 0; // number of times we STOLE an exclusive endpoint
+
     // Same as above but for SHARED endpoints.
     int32_t mSharedSearchCount    = 0;
     int32_t mSharedFoundCount     = 0;
     int32_t mSharedOpenCount      = 0;
     int32_t mSharedCloseCount     = 0;
+
+    // For easily disabling the stealing of exclusive streams.
+    static constexpr bool kStealingEnabled = true;
 };
 } /* namespace aaudio */