Removed deprecated 3-parameter PrepareMailtoHandling

Final step 5 of cleaning up the provider API for MailtoHandlerProvider.

Bug: 813821
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Ie454be3b22237a493f943869287b283e1bfe5227
Reviewed-on: https://chromium-review.googlesource.com/956237Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Peter Lee <pkl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541892}

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

@@ -9,9 +9,6 @@
 #include "base/macros.h"
 
 @class ChromeIdentity;
-namespace ios {
-class ChromeIdentityService;
-}  // namespace ios
 
 typedef ChromeIdentity* (^SignedInIdentityBlock)(void);
 typedef NSArray<ChromeIdentity*>* (^SignedInIdentitiesBlock)(void);
@@ -29,16 +26,6 @@ class MailtoHandlerProvider {
       SignedInIdentityBlock signed_in_identity_block,
       SignedInIdentitiesBlock signed_in_identities_block);
 
-  // Set up mailto handling for the currently signed in users.
-  // 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.
-  // DEPRECATED: Use the above overloaded PrepareMailtoHandling() method
-  // without |identity_service| parameter instead.
-  virtual void PrepareMailtoHandling(
-      ios::ChromeIdentityService* identity_service,
-      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

@@ -16,11 +16,6 @@ void MailtoHandlerProvider::PrepareMailtoHandling(
     SignedInIdentityBlock signed_in_identity_block,
     SignedInIdentitiesBlock signed_in_identities_block) {}
 
-void MailtoHandlerProvider::PrepareMailtoHandling(
-    ios::ChromeIdentityService* identity_service,
-    SignedInIdentityBlock signed_in_identity_block,
-    SignedInIdentitiesBlock signed_in_identities_block) {}
-
 NSString* MailtoHandlerProvider::MailtoHandlerSettingsTitle() const {
   return nil;
 }