Upstream Chrome on iOS source code [2/11].

ios/chrome/browser/metrics/size_class_recorder.h

Index: ios/chrome/browser/metrics/size_class_recorder.h
diff --git a/ios/chrome/browser/metrics/size_class_recorder.h b/ios/chrome/browser/metrics/size_class_recorder.h
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index 0000000000000000000000000000000000000000..fa5807d4fef3f69a02ebf0b02142762ede85f922
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+++ b/ios/chrome/browser/metrics/size_class_recorder.h
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+// Copyright 2015 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_METRICS_SIZE_CLASS_RECORDER_H_
+#define IOS_CHROME_BROWSER_METRICS_SIZE_CLASS_RECORDER_H_
+
+#import <UIKit/UIKit.h>
+
+// Reports metrics for the size classes uses on iPad iOS 9+.
+@interface SizeClassRecorder : NSObject
+
+- (instancetype)initWithHorizontalSizeClass:(UIUserInterfaceSizeClass)sizeClass
+    NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+// Call this method upon horizontal size class changes to report the used size
+// class to UMA. It will be reported under Tab.HorizontalSizeClassUsed.
+- (void)horizontalSizeClassDidChange:(UIUserInterfaceSizeClass)newSizeClass;
+
+// Call this class method when a page has loaded to record the size class at
+// that time. It will be reported inder Tab.PageLoadInHorizontalSizeClass.
+- (void)pageLoadedWithHorizontalSizeClass:(UIUserInterfaceSizeClass)sizeClass;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_METRICS_SIZE_CLASS_RECORDER_H_