Reenable some supressed warnings for the objc SDK.

Bug: webrtc:8441
Change-Id: I6b427dfc1fe275e274d042766e0850628cf19994
Reviewed-on: https://webrtc-review.googlesource.com/15000
Reviewed-by: Anders Carlsson <andersc@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20425}

modules/audio_device/ios/voice_processing_audio_unit.mm

@@ -424,7 +424,7 @@ AudioStreamBasicDescription VoiceProcessingAudioUnit::GetFormat(
   // - avoid resampling in the I/O unit by using the hardware sample rate
   // - linear PCM => noncompressed audio data format with one frame per packet
   // - no need to specify interleaving since only mono is supported
-  AudioStreamBasicDescription format = {0};
+  AudioStreamBasicDescription format;
   RTC_DCHECK_EQ(1, kRTCAudioSessionPreferredNumberOfChannels);
   format.mSampleRate = sample_rate;
   format.mFormatID = kAudioFormatLinearPCM;

p2p/base/port.h

@@ -432,7 +432,7 @@ class Port : public PortInterface, public rtc::MessageHandler,
   // A virtual cost perceived by the user, usually based on the network type
   // (WiFi. vs. Cellular). It takes precedence over the priority when
   // comparing two connections.
-  uint16_t network_cost_;
+  int16_t network_cost_;
   State state_ = State::INIT;
   int64_t last_time_all_connections_removed_ = 0;
 

sdk/BUILD.gn

@@ -42,6 +42,10 @@ if (is_ios || is_mac) {
       "objc/Framework/Classes/VideoToolbox",
       "objc/Framework/Headers",
     ]
+    cflags = [
+      "-Wstrict-overflow",
+      "-Wmissing-field-initializers",
+    ]
   }
 
   rtc_static_library("common_objc") {