Removed ChromeBrowserState::AsTestChromeBrowserState.

BUG=583682

Review-Url: https://codereview.chromium.org/2852673002
Cr-Commit-Position: refs/heads/master@{#467949}

ios/chrome/browser/browser_state/chrome_browser_state.h

@@ -128,13 +128,6 @@ class ChromeBrowserState : public web::BrowserState {
   virtual net::URLRequestContextGetter* CreateIsolatedRequestContext(
       const base::FilePath& partition_path) = 0;
 
-  // Returns the current ChromeBrowserState casted as a TestChromeBrowserState
-  // or null if it is not a TestChromeBrowserState.
-  // TODO(crbug.com/583682): This method should not be used. It is there for
-  // supporting a legacy test, and will be removed as soon as the deprecated
-  // test is removed.
-  virtual TestChromeBrowserState* AsTestChromeBrowserState();
-
   // web::BrowserState
   net::URLRequestContextGetter* GetRequestContext() override;
 

ios/chrome/browser/browser_state/chrome_browser_state.mm

@@ -63,10 +63,6 @@ sync_preferences::PrefServiceSyncable* ChromeBrowserState::GetSyncablePrefs() {
   return static_cast<sync_preferences::PrefServiceSyncable*>(GetPrefs());
 }
 
-TestChromeBrowserState* ChromeBrowserState::AsTestChromeBrowserState() {
-  return nullptr;
-}
-
 net::URLRequestContextGetter* ChromeBrowserState::GetRequestContext() {
   DCHECK_CURRENTLY_ON(web::WebThread::UI);
   if (!request_context_getter_) {

ios/chrome/browser/browser_state/test_chrome_browser_state.h

@@ -55,7 +55,6 @@ class TestChromeBrowserState : public ios::ChromeBrowserState {
       ProtocolHandlerMap* protocol_handlers) override;
   net::URLRequestContextGetter* CreateIsolatedRequestContext(
       const base::FilePath& partition_path) override;
-  TestChromeBrowserState* AsTestChromeBrowserState() override;
 
   // This method is defined as empty following the paradigm of
   // TestingProfile::DestroyOffTheRecordProfile().

ios/chrome/browser/browser_state/test_chrome_browser_state.mm

@@ -293,10 +293,6 @@ TestChromeBrowserState::CreateIsolatedRequestContext(
   return nullptr;
 }
 
-TestChromeBrowserState* TestChromeBrowserState::AsTestChromeBrowserState() {
-  return this;
-}
-
 void TestChromeBrowserState::CreateWebDataService() {
   ignore_result(
       ios::WebDataServiceFactory::GetInstance()->SetTestingFactoryAndUse(