Remove unused CloudPolicyService::ManagedBy()

This function was extracting domain from username in PolicyData
which could be not up-to-date after domain rename.
It's better to get rid of as much |username| usages as possible.

BUG=780792
TEST=Trybots

Change-Id: I6aba952cb63d4450863ac7f3ee30c18a3a9830d1
Reviewed-on: https://chromium-review.googlesource.com/1017122Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Sergey Poromov <poromov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551761}

components/policy/core/common/cloud/cloud_policy_service.cc

@@ -43,17 +43,6 @@ CloudPolicyService::~CloudPolicyService() {
   store_->RemoveObserver(this);
 }
 
-std::string CloudPolicyService::ManagedBy() const {
-  const em::PolicyData* policy = store_->policy();
-  if (policy) {
-    std::string username = policy->username();
-    std::size_t pos = username.find('@');
-    if (pos != std::string::npos)
-      return username.substr(pos + 1);
-  }
-  return std::string();
-}
-
 void CloudPolicyService::RefreshPolicy(const RefreshPolicyCallback& callback) {
   // If the client is not registered or is unregistering, bail out.
   if (!client_->is_registered() || unregister_state_ != UNREGISTER_NONE) {

components/policy/core/common/cloud/cloud_policy_service.h

@@ -48,10 +48,6 @@ class POLICY_EXPORT CloudPolicyService : public CloudPolicyClient::Observer,
                      CloudPolicyStore* store);
   ~CloudPolicyService() override;
 
-  // Returns the domain that manages this user/device, according to the current
-  // policy blob. Empty if not managed/not available.
-  std::string ManagedBy() const;
-
   // Refreshes policy. |callback| will be invoked after the operation completes
   // or aborts because of errors.
   void RefreshPolicy(const RefreshPolicyCallback& callback);

components/policy/core/common/cloud/cloud_policy_service_unittest.cc

@@ -51,16 +51,6 @@ MATCHER_P(ProtoMatches, proto, std::string()) {
   return arg.SerializePartialAsString() == proto.SerializePartialAsString();
 }
 
-TEST_F(CloudPolicyServiceTest, ManagedByEmptyPolicy) {
-  EXPECT_EQ(std::string(), service_.ManagedBy());
-}
-
-TEST_F(CloudPolicyServiceTest, ManagedByValidPolicy) {
-  store_.policy_.reset(new em::PolicyData());
-  store_.policy_->set_username("user@example.com");
-  EXPECT_EQ("example.com", service_.ManagedBy());
-}
-
 TEST_F(CloudPolicyServiceTest, PolicyUpdateSuccess) {
   em::PolicyFetchResponse policy;
   policy.set_policy_data("fake policy");