Hold onto linked binder.

unlinkToDeath is no longer required, (this change in behavior is to
avoid leaks) so holding onto window manager here (still calling
unlinkToDeath to avoid a log, but may for instance remove all
unlinkToDeath calls in the future).

Bug: 134576445
Test: boot
Change-Id: I78259964b564d87c4bb9be254ee46d3ce04db5ad
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 78d751a..629c6ca 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -494,9 +494,9 @@
 
     // wait patiently for the window manager death
     const String16 name("window");
-    sp<IBinder> window(defaultServiceManager()->getService(name));
-    if (window != 0) {
-        window->linkToDeath(static_cast<IBinder::DeathRecipient*>(this));
+    mWindowManager = defaultServiceManager()->getService(name);
+    if (mWindowManager != 0) {
+        mWindowManager->linkToDeath(static_cast<IBinder::DeathRecipient*>(this));
     }
 
     if (mVrFlinger) {
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 0914a09..009cf48 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -892,6 +892,9 @@
     // either AID_GRAPHICS or AID_SYSTEM.
     status_t CheckTransactCodeCredentials(uint32_t code);
 
+    // to linkToDeath
+    sp<IBinder> mWindowManager;
+
     std::unique_ptr<dvr::VrFlinger> mVrFlinger;
     std::atomic<bool> mVrFlingerRequestsDisplay;
     static bool useVrFlinger;