Remove obsolete method from MailtoHandlerProvider

The overload of PrepareMailtoHandling is no longer overridden
in the downstream implementation and not called from upstream
code so it can be safely removed.

Bug: none
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I5bde07b17f1c5293488b0d65d284fa0e0ecea5f6
Reviewed-on: https://chromium-review.googlesource.com/1106164
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568819}

ios/public/provider/chrome/browser/mailto/mailto_handler_provider.h

@@ -29,13 +29,6 @@ class MailtoHandlerProvider {
   // Unregisters the mailto handler for browser state.
   virtual void RemoveMailtoHandling();
 
-  // Deprecated: Set up mailto handling for the current user.
-  // The Signed-In Identity Block should return the primary signed in user.
-  // The Signed-In Identities Block should return all users signed in to Chrome.
-  virtual void PrepareMailtoHandling(
-      SignedInIdentityBlock signed_in_identity_block,
-      SignedInIdentitiesBlock signed_in_identities_block);
-
   // Returns a properly localized title for the menu item or button used to open
   // the settings for this handler. Returns nil if mailto handling is not
   // supported by the provider.

ios/public/provider/chrome/browser/mailto/mailto_handler_provider.mm

@@ -17,10 +17,6 @@ void MailtoHandlerProvider::PrepareMailtoHandling(
 
 void MailtoHandlerProvider::RemoveMailtoHandling() {}
 
-void MailtoHandlerProvider::PrepareMailtoHandling(
-    SignedInIdentityBlock signed_in_identity_block,
-    SignedInIdentitiesBlock signed_in_identities_block) {}
-
 NSString* MailtoHandlerProvider::MailtoHandlerSettingsTitle() const {
   return nil;
 }