Adds Compose Email Settings UI for deprecating Native App Launcher

ios/chrome/browser/web/fake_mailto_handler_helpers.h

Index: ios/chrome/browser/web/fake_mailto_handler_helpers.h
diff --git a/ios/chrome/browser/web/fake_mailto_handler_helpers.h b/ios/chrome/browser/web/fake_mailto_handler_helpers.h
new file mode 100644
index 0000000000000000000000000000000000000000..c48d7ca89ca91e9beac0c4bf8cb0b65b5b3fb3b9
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+++ b/ios/chrome/browser/web/fake_mailto_handler_helpers.h
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+// Copyright 2017 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_CHROME_BROWSER_WEB_FAKE_MAILTO_HANLDERS_H_
+#define IOS_CHROME_BROWSER_WEB_FAKE_MAILTO_HANLDERS_H_
+
+#import "ios/chrome/browser/web/mailto_handler.h"
+#import "ios/chrome/browser/web/mailto_handler_gmail.h"
+#import "ios/chrome/browser/web/mailto_url_rewriter.h"
+
+// Test fixtures for faking MailtoHandlerGmail objects that reports whether
+// Gmail app as installed or not.
+
+// Fakes Gmail handler where Gmail app is not installed.
+@interface FakeMailtoHandlerGmailNotInstalled : MailtoHandlerGmail
+@end
+
+// Fakes Gmail handler where Gmail app is installed.
+@interface FakeMailtoHandlerGmailInstalled : MailtoHandlerGmail
+@end
+
+// An observer object that counts and reports the number of times it has been
+// called by the MailtoURLRewriter object.
+@interface CountingMailtoURLRewriterObserver
+    : NSObject<MailtoURLRewriterObserver>
+// Returns the number of times that observer has been called.
+@property(nonatomic, readonly) int changeCount;
+@end
+
+#endif  // IOS_CHROME_BROWSER_WEB_FAKE_MAILTO_HANLDERS_H_