webrtc/base: Use RTC_DCHECK() instead of assert()

webrtc/base/maccocoathreadhelper.mm

Index: webrtc/base/maccocoathreadhelper.mm
diff --git a/webrtc/base/maccocoathreadhelper.mm b/webrtc/base/maccocoathreadhelper.mm
index 59ae6c4c9943f2c7cc00494177a78bc5038f3025..70d920de3980c599beaeead2d061f7f170eff3c8 100644
--- a/webrtc/base/maccocoathreadhelper.mm
+++ b/webrtc/base/maccocoathreadhelper.mm
@@ -9,11 +9,12 @@
  */
 // Helper function for using Cocoa with Posix threading.
 
-#import <assert.h>
 #import <Foundation/Foundation.h>
 
 #import "webrtc/base/maccocoathreadhelper.h"
 
+#include "webrtc/base/checks.h"
+
 namespace rtc {
 
 // Cocoa must be "put into multithreading mode" before Cocoa functionality can
@@ -34,7 +35,7 @@ void InitCocoaMultiThreading() {
     [hack drain];
   }
 
-  assert([NSThread isMultiThreaded]);
+  RTC_DCHECK([NSThread isMultiThreaded]);
 }
 
 }  // namespace rtc