Add possibility to set RTC_OBJC_TYPE_PREFIX from GN.

This CL also adds the prefix RTC_TESTING to `ios_internal_pure_release_bot_arm64` in order to avoid ODR
violations.

Bug: b/292472934
Change-Id: If63020e679c8670b4c797217eb38fc8c2954d422
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/313240
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40476}

BUILD.gn

@@ -138,6 +138,10 @@ config("common_inherited_config") {
   cflags = []
   ldflags = []
 
+  if (rtc_objc_prefix != "") {
+    defines += [ "RTC_OBJC_TYPE_PREFIX=${rtc_objc_prefix}" ]
+  }
+
   if (rtc_dlog_always_on) {
     defines += [ "DLOG_ALWAYS_ON" ]
   }

sdk/objc/base/RTCMacros.h

@@ -36,9 +36,10 @@
 // WebRTC.framework with their own prefix in case symbol clashing is a
 // problem.
 //
-// This macro must only be defined here and not on via compiler flag to
-// ensure it has a unique value.
+// This macro must be defined uniformily across all the translation units.
+#ifndef RTC_OBJC_TYPE_PREFIX
 #define RTC_OBJC_TYPE_PREFIX
+#endif
 
 // RCT_OBJC_TYPE
 //

sdk/objc/unittests/RTCPeerConnectionFactory_xctest.m

@@ -287,8 +287,8 @@
 
     __block RTC_OBJC_TYPE(RTCPeerConnectionFactory) * factory;
     __block RTC_OBJC_TYPE(RTCPeerConnection) * pc1;
-    RTCSessionDescription *rollback = [[RTCSessionDescription alloc] initWithType:RTCSdpTypeRollback
-                                                                              sdp:@""];
+    RTC_OBJC_TYPE(RTCSessionDescription) *rollback =
+        [[RTC_OBJC_TYPE(RTCSessionDescription) alloc] initWithType:RTCSdpTypeRollback sdp:@""];
 
     @autoreleasepool {
       factory = [[RTC_OBJC_TYPE(RTCPeerConnectionFactory) alloc] init];

tools_webrtc/mb/mb_config.pyl

@@ -271,7 +271,8 @@
     ],
     'ios_internal_pure_release_bot_arm64': [
       'ios', 'pure_release_bot', 'arm64',
-      'ios_code_signing_identity_description', 'xctest'
+      'ios_code_signing_identity_description', 'xctest',
+      'rtc_objc_test_prefix',
     ],
     'ios_internal_release_bot_arm64': [
       'ios', 'release_bot', 'arm64', 'ios_code_signing_identity_description',
@@ -456,6 +457,9 @@
     'release_bot': {
       'mixins': ['pure_release_bot', 'dcheck_always_on'],
     },
+    'rtc_objc_test_prefix': {
+      'gn_args': 'rtc_objc_prefix="RTC_TESTING"',
+    },
     'rtti': {
       'gn_args': 'use_rtti=true',
     },

webrtc.gni

@@ -239,6 +239,11 @@ declare_args() {
   #  "warn": RTC_LOGs a message with LS_WARNING severity if the field trial
   #          hasn't been registered.
   rtc_strict_field_trials = ""
+
+  # If different from "", symbols exported with RTC_OBJC_EXPORT will be prefixed
+  # with this string.
+  # See the definition of RTC_OBJC_TYPE_PREFIX in the code.
+  rtc_objc_prefix = ""
 }
 
 if (!build_with_mozilla) {