Wait for WWAN state to propagate to Breakpad in EG tests

ios/chrome/browser/ui/settings/settings_egtest.mm

Index: ios/chrome/browser/ui/settings/settings_egtest.mm
diff --git a/ios/chrome/browser/ui/settings/settings_egtest.mm b/ios/chrome/browser/ui/settings/settings_egtest.mm
index 6a5d36deb6b339e8f657626dac6284c139875eb4..cff3d839115ce09fc47ed2844c88c06014a6a47d 100644
--- a/ios/chrome/browser/ui/settings/settings_egtest.mm
+++ b/ios/chrome/browser/ui/settings/settings_egtest.mm
@@ -593,10 +593,12 @@ bool IsCertificateCleared() {
   // Set the network to use a cellular network, which should disable uploading
   // when the wifi-only flag is set.
   chrome_test_util::SetWWANStateTo(YES);
+  [[GREYUIThreadExecutor sharedInstance] drainUntilIdle];
   [self assertMetricsServiceEnabledButNotUploading:serviceType];
 
   // Turn off cellular network usage, which should enable uploading.
   chrome_test_util::SetWWANStateTo(NO);
+  [[GREYUIThreadExecutor sharedInstance] drainUntilIdle];
   [self assertMetricsServiceEnabled:serviceType];
 
   // kMetricsReportingEnabled ON and kMetricsReportingWifiOnly OFF