diff -r 000000000000 -r 6474c204b198 content/media/webrtc/MediaTrackConstraints.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/webrtc/MediaTrackConstraints.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,93 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This file should not be included by other includes, as it contains code
+
+#ifndef MEDIATRACKCONSTRAINTS_H_
+#define MEDIATRACKCONSTRAINTS_H_
+
+#include "mozilla/dom/MediaStreamTrackBinding.h"
+
+namespace mozilla {
+
+// Normalized internal version of MediaTrackConstraints to simplify downstream
+// processing. This implementation-only helper is included as needed by both
+// MediaManager (for gUM camera selection) and MediaEngine (for applyConstraints).
+
+template<typename T>
+class MediaTrackConstraintsN : public dom::MediaTrackConstraints
+{
+public:
+  typedef T Kind;
+  dom::Sequence<Kind> mRequireN;
+  bool mUnsupportedRequirement;
+  MediaTrackConstraintSet mRequired;
+  dom::Sequence<MediaTrackConstraintSet> mNonrequired;
+
+  MediaTrackConstraintsN(const dom::MediaTrackConstraints &aOther,
+                         const dom::EnumEntry* aStrings)
+  : dom::MediaTrackConstraints(aOther)
+  , mUnsupportedRequirement(false)
+  , mStrings(aStrings)
+  {
+    if (mRequire.WasPassed()) {
+      auto& array = mRequire.Value();
+      for (uint32_t i = 0; i < array.Length(); i++) {
+        auto value = ToEnum(array[i]);
+        if (value != Kind::Other) {
+          mRequireN.AppendElement(value);
+        } else {
+          mUnsupportedRequirement = true;
+        }
+      }
+    }
+  }
+protected:
+  MediaTrackConstraintSet& Triage(const Kind kind) {
+    if (mRequireN.IndexOf(kind) != mRequireN.NoIndex) {
+      return mRequired;
+    } else {
+      mNonrequired.AppendElement(MediaTrackConstraintSet());
+      return mNonrequired[mNonrequired.Length()-1];
+    }
+  }
+private:
+  Kind ToEnum(const nsAString& aSrc) {
+    for (size_t i = 0; mStrings[i].value; i++) {
+      if (aSrc.EqualsASCII(mStrings[i].value)) {
+        return Kind(i);
+      }
+    }
+    return Kind::Other;
+  }
+  const dom::EnumEntry* mStrings;
+};
+
+struct AudioTrackConstraintsN :
+  public MediaTrackConstraintsN<dom::SupportedAudioConstraints>
+{
+  AudioTrackConstraintsN(const dom::MediaTrackConstraints &aOther)
+  : MediaTrackConstraintsN<dom::SupportedAudioConstraints>(aOther, // B2G ICS compiler bug
+                           dom::SupportedAudioConstraintsValues::strings) {}
+};
+
+struct VideoTrackConstraintsN :
+    public MediaTrackConstraintsN<dom::SupportedVideoConstraints>
+{
+  VideoTrackConstraintsN(const dom::MediaTrackConstraints &aOther)
+  : MediaTrackConstraintsN<dom::SupportedVideoConstraints>(aOther,
+                           dom::SupportedVideoConstraintsValues::strings) {
+    if (mFacingMode.WasPassed()) {
+      Triage(Kind::FacingMode).mFacingMode.Construct(mFacingMode.Value());
+    }
+    // Reminder: add handling for new constraints both here & SatisfyConstraintSet
+    Triage(Kind::Width).mWidth = mWidth;
+    Triage(Kind::Height).mHeight = mHeight;
+    Triage(Kind::FrameRate).mFrameRate = mFrameRate;
+  }
+};
+
+}
+
+#endif /* MEDIATRACKCONSTRAINTS_H_ */