Update the MailtoHandlerProvider interface to simplify the blocks away.

Bug: 810904
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I07075a30553f1c3e2f70b1b776ea064c376ce186
Reviewed-on: https://chromium-review.googlesource.com/1018114
Commit-Queue: Daniel Blakemore <danblakemore@google.com>
Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553889}

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

@@ -8,6 +8,10 @@
 #import <UIKit/UIKit.h>
 #include "base/macros.h"
 
+namespace ios {
+class ChromeBrowserState;
+}  // namespace ios
+
 @class ChromeIdentity;
 
 typedef ChromeIdentity* (^SignedInIdentityBlock)(void);
@@ -19,7 +23,10 @@ class MailtoHandlerProvider {
   MailtoHandlerProvider();
   virtual ~MailtoHandlerProvider();
 
-  // Set up mailto handling for the current user.
+  // Set up mailto handling for the current browser state.
+  virtual void PrepareMailtoHandling(ios::ChromeBrowserState* browserState);
+
+  // 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(

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

@@ -12,6 +12,9 @@ MailtoHandlerProvider::MailtoHandlerProvider() {}
 
 MailtoHandlerProvider::~MailtoHandlerProvider() {}
 
+void MailtoHandlerProvider::PrepareMailtoHandling(
+    ios::ChromeBrowserState* browserState) {}
+
 void MailtoHandlerProvider::PrepareMailtoHandling(
     SignedInIdentityBlock signed_in_identity_block,
     SignedInIdentitiesBlock signed_in_identities_block) {}