Revert "Relands 697d4f8f after fixing upstream change."

This reverts commit 6c5d6c38.

Reason for revert: Must be rolled back in tandem with https://chrome-internal-review.googlesource.com/c/chrome/ios_internal/+/573755 

Original change's description:
> Relands 697d4f8f after fixing upstream change.
> 
> Bug: 808113
> 
> Original change's description:
> >Enables Mailto Handling with Google UI by default.
> >
> >Bug: 808113
> >Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
> >Change-Id: I2b475e6fd474c900ed1984010d15a3e1e31c2af0
> >Reviewed-on: https://chromium-review.googlesource.com/922930
> >Commit-Queue: Daniel Blakemore <danblakemore@google.com>
> >Reviewed-by: Peter Lee <pkl@chromium.org>
> >Cr-Commit-Position: refs/heads/master@{#537373}
> 
> Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
> Change-Id: I3c9821bd95d1ac74fcc4dc4b7c4474ce0b40c5da
> Reviewed-on: https://chromium-review.googlesource.com/924635
> Reviewed-by: Peter Lee <pkl@chromium.org>
> Commit-Queue: Daniel Blakemore <danblakemore@google.com>
> Cr-Commit-Position: refs/heads/master@{#537870}

TBR=pkl@chromium.org,danblakemore@google.com

Change-Id: I4f5da1bfc9fbaea35999891528d5086fb0bc9605
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 808113
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Reviewed-on: https://chromium-review.googlesource.com/927501Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537889}

ios/chrome/browser/mailto/features.mm

@@ -9,4 +9,4 @@
 #endif
 
 const base::Feature kMailtoHandledWithGoogleUI{
-    "kMailtoHandledWithGoogleUI", base::FEATURE_ENABLED_BY_DEFAULT};
+    "kMailtoHandledWithGoogleUI", base::FEATURE_DISABLED_BY_DEFAULT};

ios/public/provider/chrome/browser/BUILD.gn

@@ -36,7 +36,6 @@ source_set("test_support") {
     "//ios/public/provider/chrome/browser/distribution:test_support",
     "//ios/public/provider/chrome/browser/external_search:test_support",
     "//ios/public/provider/chrome/browser/images:test_support",
-    "//ios/public/provider/chrome/browser/mailto:test_support",
     "//ios/public/provider/chrome/browser/omaha:test_support",
     "//ios/public/provider/chrome/browser/signin:test_support",
     "//ios/public/provider/chrome/browser/spotlight:test_support",

ios/public/provider/chrome/browser/mailto/BUILD.gn

@@ -12,15 +12,3 @@ source_set("mailto") {
     "//base",
   ]
 }
-
-source_set("test_support") {
-  configs += [ "//build/config/compiler:enable_arc" ]
-  testonly = true
-  sources = [
-    "test_mailto_handler_provider.h",
-    "test_mailto_handler_provider.mm",
-  ]
-  deps = [
-    ":mailto",
-  ]
-}

ios/public/provider/chrome/browser/mailto/mailto_handler_provider.h

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef IOS_PUBLIC_PROVIDER_CHROME_BROWSER_MAILTO_MAILTO_HANDLER_PROVIDER_H_
-#define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_MAILTO_MAILTO_HANDLER_PROVIDER_H_
+#ifndef IOS_INTERNAL_CHROME_BROWSER_PROVIDERS_MAILTO_MAILTO_HANDLER_PROVIDER_H_
+#define IOS_INTERNAL_CHROME_BROWSER_PROVIDERS_MAILTO_MAILTO_HANDLER_PROVIDER_H_
 
 #import <UIKit/UIKit.h>
 #include "base/macros.h"
@@ -46,4 +46,4 @@ class MailtoHandlerProvider {
   DISALLOW_COPY_AND_ASSIGN(MailtoHandlerProvider);
 };
 
-#endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_MAILTO_MAILTO_HANDLER_PROVIDER_H_
+#endif  // IOS_INTERNAL_CHROME_BROWSER_PROVIDERS_MAILTO_MAILTO_HANDLER_PROVIDER_H_

ios/public/provider/chrome/browser/mailto/test_mailto_handler_provider.h

-// Copyright 2018 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef IOS_PUBLIC_PROVIDER_CHROME_BROWSER_MAILTO_TEST_MAILTO_HANDLER_PROVIDER_H_
-#define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_MAILTO_TEST_MAILTO_HANDLER_PROVIDER_H_
-
-#import "ios/public/provider/chrome/browser/mailto/mailto_handler_provider.h"
-
-// An provider to handle the opening of mailto links.
-class TestMailtoHandlerProvider : public MailtoHandlerProvider {
- public:
-  TestMailtoHandlerProvider();
-  ~TestMailtoHandlerProvider() override;
-
-  UIViewController* MailtoHandlerSettingsController() const override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(TestMailtoHandlerProvider);
-};
-
-#endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_MAILTO_TEST_MAILTO_HANDLER_PROVIDER_H_

ios/public/provider/chrome/browser/mailto/test_mailto_handler_provider.mm

-// Copyright 2018 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#import "ios/public/provider/chrome/browser/mailto/test_mailto_handler_provider.h"
-
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
-
-TestMailtoHandlerProvider::TestMailtoHandlerProvider() {}
-
-TestMailtoHandlerProvider::~TestMailtoHandlerProvider() {}
-
-UIViewController* TestMailtoHandlerProvider::MailtoHandlerSettingsController()
-    const {
-  // Return something other than nil.
-  return [[UIViewController alloc] init];
-}

ios/public/provider/chrome/browser/test_chrome_browser_provider.h

@@ -36,7 +36,6 @@ class TestChromeBrowserProvider : public ChromeBrowserProvider {
   ExternalSearchProvider* GetExternalSearchProvider() const override;
   void CheckForFirstPartyApps() const override;
   BrandedImageProvider* GetBrandedImageProvider() const override;
-  MailtoHandlerProvider* GetMailtoHandlerProvider() const override;
 
  private:
   std::unique_ptr<AppDistributionProvider> app_distribution_provider_;
@@ -48,7 +47,6 @@ class TestChromeBrowserProvider : public ChromeBrowserProvider {
   std::unique_ptr<UserFeedbackProvider> user_feedback_provider_;
   std::unique_ptr<SpotlightProvider> spotlight_provider_;
   std::unique_ptr<ExternalSearchProvider> external_search_provider_;
-  std::unique_ptr<MailtoHandlerProvider> mailto_handler_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(TestChromeBrowserProvider);
 };

ios/public/provider/chrome/browser/test_chrome_browser_provider.mm

@@ -10,7 +10,6 @@
 #include "ios/public/provider/chrome/browser/distribution/test_app_distribution_provider.h"
 #include "ios/public/provider/chrome/browser/external_search/test_external_search_provider.h"
 #include "ios/public/provider/chrome/browser/images/test_branded_image_provider.h"
-#include "ios/public/provider/chrome/browser/mailto/test_mailto_handler_provider.h"
 #include "ios/public/provider/chrome/browser/omaha/test_omaha_service_provider.h"
 #include "ios/public/provider/chrome/browser/signin/fake_chrome_identity_service.h"
 #include "ios/public/provider/chrome/browser/signin/test_signin_resources_provider.h"
@@ -36,8 +35,8 @@ TestChromeBrowserProvider::TestChromeBrowserProvider()
       voice_search_provider_(std::make_unique<TestVoiceSearchProvider>()),
       user_feedback_provider_(std::make_unique<TestUserFeedbackProvider>()),
       spotlight_provider_(std::make_unique<TestSpotlightProvider>()),
-      external_search_provider_(std::make_unique<TestExternalSearchProvider>()),
-      mailto_handler_provider_(std::make_unique<TestMailtoHandlerProvider>()) {}
+      external_search_provider_(
+          std::make_unique<TestExternalSearchProvider>()) {}
 
 TestChromeBrowserProvider::~TestChromeBrowserProvider() {}
 
@@ -105,9 +104,4 @@ BrandedImageProvider* TestChromeBrowserProvider::GetBrandedImageProvider()
   return branded_image_provider_.get();
 }
 
-MailtoHandlerProvider* TestChromeBrowserProvider::GetMailtoHandlerProvider()
-    const {
-  return mailto_handler_provider_.get();
-}
-
 }  // namespace ios