Make fps NSInteger in startCaptureWithDevice.

This is better in line with Obj-C design guidelines.

BUG=None

Review-Url: https://codereview.webrtc.org/2862493003
Cr-Commit-Position: refs/heads/master@{#18023}

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCCameraVideoCapturer.h

@@ -31,7 +31,7 @@ RTC_EXPORT
 // Starts and stops the capture session asynchronously.
 - (void)startCaptureWithDevice:(AVCaptureDevice *)device
                         format:(AVCaptureDeviceFormat *)format
-                           fps:(int)fps;
+                           fps:(NSInteger)fps;
 // Stops the capture session asynchronously.
 - (void)stopCapture;