Extract iOS SDK helpers to separate target.

webrtc/sdk/BUILD.gn

Index: webrtc/sdk/BUILD.gn
diff --git a/webrtc/sdk/BUILD.gn b/webrtc/sdk/BUILD.gn
index 8c8cade1d79c02f7e65dcdb05c06b2af454585ab..3ecac2f35ada5e52cdb0d114274a150d437c53ba 100644
--- a/webrtc/sdk/BUILD.gn
+++ b/webrtc/sdk/BUILD.gn
@@ -27,6 +27,21 @@ if (is_ios || is_mac) {
     ]
   }
 
+  rtc_static_library("rtc_sdk_helpers_objc") {
+    sources = [
+      "objc/Framework/Classes/helpers.h",
+      "objc/Framework/Classes/helpers.mm",
+    ]
+    deps = [
+      "../base:rtc_base_approved",
+    ]
+    configs += [ "..:common_objc" ]
+
+    if (is_ios) {
+      libs = [ "AVFoundation.framework" ]
+    }
+  }
+
   rtc_static_library("rtc_sdk_common_objc") {
     sources = [
       "objc/Framework/Classes/NSString+StdString.h",
@@ -39,8 +54,6 @@ if (is_ios || is_mac) {
       "objc/Framework/Classes/RTCMetricsSampleInfo.mm",
       "objc/Framework/Classes/RTCSSLAdapter.mm",
       "objc/Framework/Classes/RTCTracing.mm",
-      "objc/Framework/Classes/helpers.h",
-      "objc/Framework/Classes/helpers.mm",
       "objc/Framework/Headers/WebRTC/RTCDispatcher.h",
       "objc/Framework/Headers/WebRTC/RTCFieldTrials.h",
       "objc/Framework/Headers/WebRTC/RTCLogging.h",
@@ -51,6 +64,7 @@ if (is_ios || is_mac) {
       "objc/Framework/Headers/WebRTC/RTCTracing.h",
     ]
     deps = [
+      ":rtc_sdk_helpers_objc",
       "../base:rtc_base",
     ]
     configs += [ "..:common_objc" ]