Roll ios_internal from c8934873ae2c to 21c4df6218a4

c8934873ae..21c4df6218

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://skia-autoroll.corp.goog/r/ios-internal-chromium-autoroll
Please CC chrome-brapp-engprod@google.com,guiperez@google.com,tinazwang@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Bug: chromium:1513366
Change-Id: If5dc5ee9d4186186ef01917af9b4fb1b3cdf6af4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5173691
Commit-Queue: chromium-internal-autoroll <chromium-internal-autoroll@skia-corp.google.com.iam.gserviceaccount.com>
Bot-Commit: chromium-internal-autoroll <chromium-internal-autoroll@skia-corp.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1243450}

DEPS

@@ -4004,7 +4004,7 @@ deps = {
 
   'src/ios_internal':  {
       'url': Var('chrome_git') + '/chrome/ios_internal.git' + '@' +
-        'c8934873ae2cfef26a2aca3b4f31ffd2632fbdbc',
+        '21c4df6218a4dbf267fbfc9a72fd891622e152dc',
       'condition': 'checkout_ios and checkout_src_internal',
   },