Bug 1180993 - Part 3: Correct use sites of functions which return already_AddRefed. r=ehsan

dom/base/ImageEncoder.cpp

@@ -10,6 +10,7 @@
 #include "mozilla/gfx/DataSurfaceHelpers.h"
 #include "mozilla/RefPtr.h"
 #include "mozilla/SyncRunnable.h"
+#include "mozilla/unused.h"
 #include "gfxUtils.h"
 #include "nsNetUtil.h"
 
@@ -206,7 +207,7 @@ public:
     rv = NS_DispatchToMainThread(mEncodingCompleteEvent);
     if (NS_FAILED(rv)) {
       // Better to leak than to crash.
-      mEncodingCompleteEvent.forget();
+      unused << mEncodingCompleteEvent.forget();
       return rv;
     }
 

dom/ipc/TabParent.cpp

@@ -225,7 +225,7 @@ private:
             // Intentionally leak the runnable (but not the fd) rather
             // than crash when trying to release a main thread object
             // off the main thread.
-            mTabParent.forget();
+            mozilla::unused << mTabParent.forget();
             CloseFile();
         }
     }

dom/storage/DOMStorageDBThread.cpp

@@ -423,8 +423,7 @@ nsReverseStringSQLFunction::OnFunctionCall(
   rv = outVar->SetAsAUTF8String(result);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = outVar.get();
-  outVar.forget();
+  outVar.forget(aResult);
   return NS_OK;
 }
 

netwerk/cache2/CacheIndex.cpp

@@ -21,6 +21,7 @@
 #include "mozilla/AutoRestore.h"
 #include <algorithm>
 #include "mozilla/Telemetry.h"
+#include "mozilla/unused.h"
 
 
 #define kMinUnwrittenChanges   300
@@ -3045,7 +3046,7 @@ CacheIndex::FinishUpdate(bool aSucceeded)
       NS_WARNING(("CacheIndex::FinishUpdate() - Leaking mDirEnumerator!"));
       // This can happen only in case dispatching event to IO thread failed in
       // CacheIndex::PreShutdown().
-      mDirEnumerator.forget(); // Leak it since dir enumerator is not threadsafe
+      unused << mDirEnumerator.forget(); // Leak it since dir enumerator is not threadsafe
     } else {
       mDirEnumerator->Close();
       mDirEnumerator = nullptr;

widget/gtk/nsSound.cpp

@@ -24,6 +24,7 @@
 #include "nsDirectoryServiceDefs.h"
 #include "mozilla/FileUtils.h"
 #include "mozilla/Services.h"
+#include "mozilla/unused.h"
 #include "nsIStringBundle.h"
 #include "nsIXULAppInfo.h"
 #include "nsContentUtils.h"
@@ -80,7 +81,7 @@ struct ScopedCanberraFile {
     }
 
     void forget() {
-        mFile.forget();
+        mozilla::unused << mFile.forget();
     }
     nsIFile* operator->() { return mFile; }
     operator nsIFile*() { return mFile; }