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

ios/chrome/browser/metrics/tab_usage_recorder_delegate.h

Index: ios/chrome/browser/metrics/tab_usage_recorder_delegate.h
diff --git a/ios/chrome/browser/metrics/tab_usage_recorder_delegate.h b/ios/chrome/browser/metrics/tab_usage_recorder_delegate.h
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index 0000000000000000000000000000000000000000..74046a4fbcb2cbda067322f37f4e2d75cdc16aed
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+++ b/ios/chrome/browser/metrics/tab_usage_recorder_delegate.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_TAB_USAGE_RECORDER_DELEGATE_H_
+#define IOS_CHROME_BROWSER_METRICS_TAB_USAGE_RECORDER_DELEGATE_H_
+
+#import <Foundation/Foundation.h>
+
+// A delegate which provides to the TabUsageRecorder a count of how many alive
+// tabs it is monitoring.
+@protocol TabUsageRecorderDelegate
+
+// A count of how many alive tabs the TabUsageRecorder is monitoring.
+// NOTE: This should be used for metrics-gathering only; for any other purpose
+// callers should not know or care how many tabs are alive.
+- (NSUInteger)liveTabsCount;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_METRICS_TAB_USAGE_RECORDER_DELEGATE_H_