Add comments for the usage of Chrome and Google strings and logos.

ios/chrome/app/strings/ios_strings.grd

Index: ios/chrome/app/strings/ios_strings.grd
diff --git a/ios/chrome/app/strings/ios_strings.grd b/ios/chrome/app/strings/ios_strings.grd
index 9e80d6524ddb719ddfac02281f876bba255dd800..1b41ff6db03e7de3d9766a568a789eee61dd783a 100644
--- a/ios/chrome/app/strings/ios_strings.grd
+++ b/ios/chrome/app/strings/ios_strings.grd
@@ -155,6 +155,7 @@ locale.  The strings in this file are specific to iOS.
       <message name="IDS_IOS_ACCOUNT_CONSISTENCY_CONFIRMATION_SYNC_DESCRIPTION" desc="Description of the Chrome sync section on the sign-in confirmation screen. [Length: unlimited]">
         Your bookmarks, history, passwords, and other settings will be synced to your Google Account so you can use them on all your devices.
       </message>
+      <!-- "Chrome sync" is the Google Cloud Based service used for sync. Thus this string resource is set to "Chrome sync" even for Chromium builds. -->
       <message name="IDS_IOS_ACCOUNT_CONSISTENCY_CONFIRMATION_SYNC_TITLE" desc="Title of the Chrome sync section on the sign-in confirmation screen. [Length: 50em]">
         Chrome Sync
       </message>