[ios] Adds the LogoAnimationController protocol.

ios/public/provider/chrome/browser/voice/logo_animation_controller.h

+// Copyright 2016 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_VOICE_LOGO_ANIMATION_CONTROLLER_H_
+#define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_VOICE_LOGO_ANIMATION_CONTROLLER_H_
+
+#include <Foundation/Foundation.h>
+
+@protocol LogoAnimationControllerOwner;
+@protocol LogoAnimationControllerOwnerOwner;
+
+typedef NS_ENUM(NSUInteger, LogoAnimationControllerLogoState) {
+  // A state in which the logo is displayed.
+  LogoAnimationControllerLogoStateLogo,
+  // A state in which the microphone icon is displayed.
+  LogoAnimationControllerLogoStateMic,
+};
+
+#pragma mark LogoAnimationController
+
+// Protocol for objects that act as logo animation controllers.
+@protocol LogoAnimationController<NSObject>
+@end
+
+#pragma mark LogoAnimationControllerOwner
+
+// Protocol used to transfer ownership of LogoAnimationControllers between
+// objects.
+@protocol LogoAnimationControllerOwner
+
+// The controller to be used during the animation.  Setting this property to a
+// new controller transfers ownership to the receiver, and resetting it to nil
+// relinquishes the receiver's ownership of the object.  When this property is
+// set, the owner must add the new controller's view to its view hierarchy and
+// remove the old controller's view.
+@property(nonatomic, strong) id<LogoAnimationController>
+    logoAnimationController;
+
+// The default state used when the LogoAnimationController owned by the
+// receiver is not showing dots or animating.
+@property(nonatomic, readonly)
+    LogoAnimationControllerLogoState defaultLogoState;
+@end
+
+#pragma mark LogoAnimationControllerOwnerOwner
+
+// Protocol for objects that potentially own LogoAnimationControllerOwners and
+// sometimes (but not always) use them to display UI.  This extra layer of
+// indirection is necessary to decide whether to reparent animation views during
+// transition animations, as simply checking whether a
+// LogoAnimationControllerOwner's logoAnimationController is nil is
+// insufficient.  This is because a LogoAnimationController may have been
+// reparented, but its LogoAnimationControllerOwner should still be used as the
+// endpoint in the animation if it is in a state where it can be displayed.
+@protocol LogoAnimationControllerOwnerOwner
+
+// The LogoAnimationControllerOwner held by the conforming object.
+@property(nonatomic, readonly) id<LogoAnimationControllerOwner>
+    logoAnimationControllerOwner;
+
+@end
+
+#endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_VOICE_LOGO_ANIMATION_CONTROLLER_H_