Expose media constraint string constants as ObjC NSStrings

webrtc/sdk/objc/Framework/Classes/RTCMediaConstraints.mm

Index: webrtc/sdk/objc/Framework/Classes/RTCMediaConstraints.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCMediaConstraints.mm b/webrtc/sdk/objc/Framework/Classes/RTCMediaConstraints.mm
index 11be2ec026c61c8a1e0016c90820b3738fc9a6c7..f0f3c860b20d7206a19042ade5a304d9290ec998 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCMediaConstraints.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCMediaConstraints.mm
@@ -14,6 +14,23 @@
 
 #include <memory>
 
+NSString * const kRTCMediaConstraintsMinAspectRatio =
+    @(webrtc::MediaConstraintsInterface::kMinAspectRatio);
+NSString * const kRTCMediaConstraintsMaxAspectRatio =
+    @(webrtc::MediaConstraintsInterface::kMaxAspectRatio);
+NSString * const kRTCMediaConstraintsMinWidth =
+    @(webrtc::MediaConstraintsInterface::kMinWidth);
+NSString * const kRTCMediaConstraintsMaxWidth =
+    @(webrtc::MediaConstraintsInterface::kMaxWidth);
+NSString * const kRTCMediaConstraintsMinHeight =
+    @(webrtc::MediaConstraintsInterface::kMinHeight);
+NSString * const kRTCMediaConstraintsMaxHeight =
+    @(webrtc::MediaConstraintsInterface::kMaxHeight);
+NSString * const kRTCMediaConstraintsMinFrameRate =
+    @(webrtc::MediaConstraintsInterface::kMinFrameRate);
+NSString * const kRTCMediaConstraintsMaxFrameRate =
+    @(webrtc::MediaConstraintsInterface::kMaxFrameRate);
+
 namespace webrtc {
 
 MediaConstraints::~MediaConstraints() {}