Fixup of how AutofillClient impls get IdentityManager after r537790

https://chromium-review.googlesource.com/904992 added a new
AutofillClient::GetIdentityManager() interface. That CL mistakenly
had the ChromeAutofillClient and ChromeAutofillClientIOS implementations
return the IdentityManager instance associated with the current Profile.
It should actually be the IdentityManager instance associated with the
*original Profile* (/ChromeBrowserState) to be parallel with those
clients' constructions of the ProfileIdentityProvider instances whose
usage IdentityManager is replacing in //components/autofill.

Note that I verified that these are the only client implementations that
need this fix:

- AWAutofillClient returns nullptr for both the IdentityProvider and the
IdentityManager.
- WebViewAutofillClient (in //ios) doesn't use the original
  ChromeBrowserState for anything, I assume because it doesn't have
  incognito.

This bug was uncovered by the UBSanVptr bot. Thanks, UBSanVptr bot!

Bug: 798413, 814308
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I3e87888bc622204a29b4f9d3990fa39e8b165eb3
Reviewed-on: https://chromium-review.googlesource.com/928654Reviewed-by: Mathieu Perreault <mathp@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Jared Saul <jsaul@google.com>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539451}

chrome/browser/ui/autofill/chrome_autofill_client.cc

@@ -132,7 +132,8 @@ syncer::SyncService* ChromeAutofillClient::GetSyncService() {
 identity::IdentityManager* ChromeAutofillClient::GetIdentityManager() {
   Profile* profile =
       Profile::FromBrowserContext(web_contents()->GetBrowserContext());
-  return IdentityManagerFactory::GetInstance()->GetForProfile(profile);
+  return IdentityManagerFactory::GetInstance()->GetForProfile(
+      profile->GetOriginalProfile());
 }
 
 IdentityProvider* ChromeAutofillClient::GetIdentityProvider() {

ios/chrome/browser/ui/autofill/chrome_autofill_client_ios.mm

@@ -49,7 +49,7 @@ ChromeAutofillClientIOS::ChromeAutofillClientIOS(
       bridge_(bridge),
       identity_manager_(
           IdentityManagerFactory::GetInstance()->GetForBrowserState(
-              browser_state)),
+              browser_state->GetOriginalChromeBrowserState())),
       identity_provider_(std::move(identity_provider)),
       autofill_web_data_service_(
           ios::WebDataServiceFactory::GetAutofillWebDataForBrowserState(