Camera: Guard against asBinder() calls on NULL interfaces

Bug: 18207548
Change-Id: I9879c9b4c0282a6b96b77398f62beedc47f7f0a0
diff --git a/services/camera/libcameraservice/common/Camera2ClientBase.cpp b/services/camera/libcameraservice/common/Camera2ClientBase.cpp
index d6db151..eb91bd4 100644
--- a/services/camera/libcameraservice/common/Camera2ClientBase.cpp
+++ b/services/camera/libcameraservice/common/Camera2ClientBase.cpp
@@ -128,7 +128,8 @@
     String8 result;
     result.appendFormat("Camera2ClientBase[%d] (%p) PID: %d, dump:\n",
             TClientBase::mCameraId,
-            TClientBase::getRemoteCallback()->asBinder().get(),
+            (TClientBase::getRemoteCallback() != NULL ?
+                    TClientBase::getRemoteCallback()->asBinder().get() : NULL),
             TClientBase::mClientPid);
     result.append("  State: ");