Fixing some of the issues found by clang static analyzer.

Bug: webrtc:8737
Change-Id: Ib436449c493336e7c35a72a96dc88cccdbb5bbaf
Reviewed-on: https://webrtc-review.googlesource.com/39200
Commit-Queue: Peter Hanspers <peterhanspers@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21607}

sdk/objc/Framework/Classes/PeerConnection/RTCAudioTrack.mm

@@ -31,7 +31,7 @@
   std::string nativeId = [NSString stdStringForString:trackId];
   rtc::scoped_refptr<webrtc::AudioTrackInterface> track =
       factory.nativeFactory->CreateAudioTrack(nativeId, source.nativeAudioSource);
-  if ([self initWithNativeTrack:track type:RTCMediaStreamTrackTypeAudio]) {
+  if (self = [self initWithNativeTrack:track type:RTCMediaStreamTrackTypeAudio]) {
     _source = source;
   }
   return self;

sdk/objc/Framework/Classes/PeerConnection/RTCConfiguration+Private.h

@@ -62,8 +62,7 @@ NS_ASSUME_NONNULL_BEGIN
  * RTCConfiguration struct representation of this RTCConfiguration. This is
  * needed to pass to the underlying C++ APIs.
  */
-- (webrtc::PeerConnectionInterface::RTCConfiguration *)
-    createNativeConfiguration;
+- (nullable webrtc::PeerConnectionInterface::RTCConfiguration *)createNativeConfiguration;
 
 - (instancetype)initWithNativeConfiguration:
     (const webrtc::PeerConnectionInterface::RTCConfiguration &)config NS_DESIGNATED_INITIALIZER;

sdk/objc/Framework/Classes/PeerConnection/RTCEncodedImage.mm

@@ -48,7 +48,7 @@
     _frameType = static_cast<RTCFrameType>(encodedImage._frameType);
     _rotation = static_cast<RTCVideoRotation>(encodedImage.rotation_);
     _completeFrame = encodedImage._completeFrame;
-    _qp = encodedImage.qp_ == -1 ? nil : @(encodedImage.qp_);
+    _qp = @(encodedImage.qp_);
     _contentType = (encodedImage.content_type_ == webrtc::VideoContentType::SCREENSHARE) ?
         RTCVideoContentTypeScreenshare :
         RTCVideoContentTypeUnspecified;

sdk/objc/Framework/Classes/PeerConnection/RTCFileVideoCapturer.m

@@ -139,6 +139,7 @@ typedef NS_ENUM(NSInteger, RTCFileVideoCapturerStatus) {
   }
   if (CMSampleBufferGetNumSamples(sampleBuffer) != 1 || !CMSampleBufferIsValid(sampleBuffer) ||
       !CMSampleBufferDataIsReady(sampleBuffer)) {
+    CFRelease(sampleBuffer);
     [self readNextBuffer];
     return;
   }

sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnection+DataChannel.mm

@@ -16,9 +16,8 @@
 
 @implementation RTCPeerConnection (DataChannel)
 
-- (RTCDataChannel *)dataChannelForLabel:(NSString *)label
-                          configuration:
-    (RTCDataChannelConfiguration *)configuration {
+- (nullable RTCDataChannel *)dataChannelForLabel:(NSString *)label
+                                   configuration:(RTCDataChannelConfiguration *)configuration {
   std::string labelString = [NSString stdStringForString:label];
   const webrtc::DataChannelInit nativeInit =
       configuration.nativeDataChannelInit;

sdk/objc/Framework/Classes/PeerConnection/RTCRtpReceiver.mm

@@ -58,7 +58,7 @@ void RtpReceiverDelegateAdapter::OnFirstPacketReceived(
   }
 }
 
-- (RTCMediaStreamTrack *)track {
+- (nullable RTCMediaStreamTrack *)track {
   rtc::scoped_refptr<webrtc::MediaStreamTrackInterface> nativeTrack(
     _nativeRtpReceiver->track());
   if (nativeTrack) {

sdk/objc/Framework/Classes/PeerConnection/RTCSessionDescription+Private.h

@@ -21,8 +21,7 @@ NS_ASSUME_NONNULL_BEGIN
  * RTCSessionDescription object. This is needed to pass to the underlying C++
  * APIs.
  */
-@property(nonatomic, readonly)
-    webrtc::SessionDescriptionInterface *nativeDescription;
+@property(nonatomic, readonly, nullable) webrtc::SessionDescriptionInterface *nativeDescription;
 
 /**
  * Initialize an RTCSessionDescription from a native

sdk/objc/Framework/Classes/PeerConnection/RTCVideoTrack.mm

@@ -32,7 +32,7 @@
   rtc::scoped_refptr<webrtc::VideoTrackInterface> track =
       factory.nativeFactory->CreateVideoTrack(nativeId,
                                               source.nativeVideoSource);
-  if ([self initWithNativeTrack:track type:RTCMediaStreamTrackTypeVideo]) {
+  if (self = [self initWithNativeTrack:track type:RTCMediaStreamTrackTypeVideo]) {
     _source = source;
   }
   return self;

sdk/objc/Framework/Classes/PeerConnection/RTCWrappedNativeVideoDecoder.mm

@@ -49,7 +49,7 @@
 - (NSInteger)decode:(RTCEncodedImage *)encodedImage
           missingFrames:(BOOL)missingFrames
     fragmentationHeader:(RTCRtpFragmentationHeader *)fragmentationHeader
-      codecSpecificInfo:(__nullable id<RTCCodecSpecificInfo>)info
+      codecSpecificInfo:(nullable id<RTCCodecSpecificInfo>)info
            renderTimeMs:(int64_t)renderTimeMs {
   RTC_NOTREACHED();
   return 0;

sdk/objc/Framework/Classes/PeerConnection/RTCWrappedNativeVideoEncoder.mm

@@ -47,7 +47,7 @@
 }
 
 - (NSInteger)encode:(RTCVideoFrame *)frame
-    codecSpecificInfo:(id<RTCCodecSpecificInfo>)info
+    codecSpecificInfo:(nullable id<RTCCodecSpecificInfo>)info
            frameTypes:(NSArray<NSNumber *> *)frameTypes {
   RTC_NOTREACHED();
   return 0;