This CL replaces e-mail with AccountId on user selection screen.

components/signin/core/account_id/account_id.cc

Index: components/signin/core/account_id/account_id.cc
diff --git a/components/signin/core/account_id/account_id.cc b/components/signin/core/account_id/account_id.cc
index 65b237fa2758b5c19d604db08dc0259f9b0338c2..7f44c33f5e90faf67c742cedb19860f525af7967 100644
--- a/components/signin/core/account_id/account_id.cc
+++ b/components/signin/core/account_id/account_id.cc
@@ -6,7 +6,10 @@
 
 #include <functional>
 
+#include "base/json/json_reader.h"
+#include "base/json/json_writer.h"
 #include "base/memory/singleton.h"
+#include "base/values.h"
 #include "google_apis/gaia/gaia_auth_util.h"
 
 namespace {
@@ -14,6 +17,10 @@ namespace {
 // Known account types.
 const char kGoogle[] = "google";
 
+// Serialization keys
+const char kGaiaIdKey[] = "g";
+const char kEmailKey[] = "e";

[stevenjb, 2015/11/11 20:39:23]

nit: Use 'gaia' and 'email' even short term.

[Alexander Alekseev, 2015/11/12 06:53:04]

Done.

+
 struct GoogleStringSingleton {
   GoogleStringSingleton() : google(kGoogle) {}
 
@@ -115,6 +122,45 @@ AccountId AccountId::FromUserEmailGaiaId(const std::string& email,
   return AccountId(gaia_id, email);
 }
 
+std::string AccountId::Serialize() const {
+  base::DictionaryValue value;
+  value.SetString(kGaiaIdKey, gaia_id_);
+  value.SetString(kEmailKey, user_email_);
+
+  std::string serialized;
+  base::JSONWriter::Write(value, &serialized);
+  return serialized;
+}
+
+// static
+bool AccountId::Deserialize(const std::string& serialized,
+                            AccountId* account_id) {
+  base::JSONReader reader;
+  scoped_ptr<const base::Value> value(reader.Read(serialized));
+  const base::DictionaryValue* dictionary_value = NULL;
+
+  if (!value || !value->GetAsDictionary(&dictionary_value)) {
+    return false;
+  }

[stevenjb, 2015/11/11 20:39:23]

nit: no {}

[Alexander Alekseev, 2015/11/12 06:53:04]

Done.

+
+  std::string gaia_id;
+  std::string user_email;
+
+  const bool found_gaia_id = dictionary_value->GetString(kGaiaIdKey, &gaia_id);
+  const bool found_user_email =
+      dictionary_value->GetString(kEmailKey, &user_email);
+
+  DCHECK(found_gaia_id);
+  DCHECK(found_user_email);
+
+  if (!found_gaia_id && !found_user_email)
+    return false;

[stevenjb, 2015/11/11 20:39:23]

We shouldn't combine DCHECK and if(). Log an error here instead of the DCHECKs
above.

[Alexander Alekseev, 2015/11/12 06:53:04]

Done.

+
+  *account_id = FromUserEmailGaiaId(user_email, gaia_id);
+
+  return true;
+}
+
 const AccountId& EmptyAccountId() {
   return AccountId::EmptyAccountId::GetInstance()->user_id;
 }