Use 15fps for iPhone 4S

NOTRY=True
BUG=

Review-Url: https://codereview.webrtc.org/2188883002
Cr-Commit-Position: refs/heads/master@{#13564}
diff --git a/webrtc/sdk/sdk.gyp b/webrtc/sdk/sdk.gyp
index 26142e5..6f46674 100644
--- a/webrtc/sdk/sdk.gyp
+++ b/webrtc/sdk/sdk.gyp
@@ -57,7 +57,9 @@
                 'objc/Framework/Classes/RTCCameraPreviewView.m',
                 'objc/Framework/Classes/RTCUIApplication.h',
                 'objc/Framework/Classes/RTCUIApplication.mm',
+                'objc/Framework/Classes/UIDevice+RTCDevice.mm',
                 'objc/Framework/Headers/WebRTC/RTCCameraPreviewView.h',
+                'objc/Framework/Headers/WebRTC/UIDevice+RTCDevice.h',
               ],
               'link_settings': {
                 'xcode_settings': {
@@ -273,6 +275,7 @@
             'objc/Framework/Headers/WebRTC/RTCVideoRenderer.h',
             'objc/Framework/Headers/WebRTC/RTCVideoSource.h',
             'objc/Framework/Headers/WebRTC/RTCVideoTrack.h',
+            'objc/Framework/Headers/WebRTC/UIDevice+RTCDevice.h',
             'objc/Framework/Headers/WebRTC/WebRTC.h',
           ],
           'dependencies': [