Change GetAccessToken APIs so that they don't pass const ref to blocks.

ios/public/provider/chrome/browser/signin/chrome_identity_service.mm

Index: ios/public/provider/chrome/browser/signin/chrome_identity_service.mm
diff --git a/ios/public/provider/chrome/browser/signin/chrome_identity_service.mm b/ios/public/provider/chrome/browser/signin/chrome_identity_service.mm
index c2e347eba433ba36fa428ece3d6c227f5dc6f808..be02f6382dfef474f1eaef78d3d93541769f2a21 100644
--- a/ios/public/provider/chrome/browser/signin/chrome_identity_service.mm
+++ b/ios/public/provider/chrome/browser/signin/chrome_identity_service.mm
@@ -77,17 +77,15 @@ NSArray* ChromeIdentityService::GetAllIdentitiesSortedForDisplay() const {
 void ChromeIdentityService::ForgetIdentity(ChromeIdentity* identity,
                                            ForgetIdentityCallback callback) {}
 
-void ChromeIdentityService::GetAccessToken(
-    ChromeIdentity* identity,
-    const std::set<std::string>& scopes,
-    const AccessTokenCallback& callback) {}
-
-void ChromeIdentityService::GetAccessToken(
-    ChromeIdentity* identity,
-    const std::string& client_id,
-    const std::string& client_secret,
-    const std::set<std::string>& scopes,
-    const AccessTokenCallback& callback) {}
+void ChromeIdentityService::GetAccessToken(ChromeIdentity* identity,
+                                           const std::set<std::string>& scopes,
+                                           AccessTokenCallback callback) {}
+
+void ChromeIdentityService::GetAccessToken(ChromeIdentity* identity,
+                                           const std::string& client_id,
+                                           const std::string& client_secret,
+                                           const std::set<std::string>& scopes,
+                                           AccessTokenCallback callback) {}
 
 void ChromeIdentityService::GetAvatarForIdentity(ChromeIdentity* identity,
                                                  GetAvatarCallback callback) {}