Upstream various ios/web utilities and helpers

ios/web/crw_network_activity_indicator_manager.h

Index: ios/web/crw_network_activity_indicator_manager.h
diff --git a/ios/web/crw_network_activity_indicator_manager.h b/ios/web/crw_network_activity_indicator_manager.h
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+// Copyright 2014 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_WEB_CRW_NETWORK_ACTIVITY_INDICATOR_MANAGER_H_
+#define IOS_WEB_CRW_NETWORK_ACTIVITY_INDICATOR_MANAGER_H_
+
+#import <Foundation/Foundation.h>
+
+// This class controls access to the network activity indicator across the
+// app. It provides a simple interface for clients to indicate they are
+// starting a network task and they would like the indicator shown, and to
+// indicate they have finished a network task.
+//
+// Clients are required to pass an NSString* to each method to identify
+// themselves. Separating clients into groups prevents a client from "stopping"
+// requests from other clients on accident, and makes those bugs easier to
+// track down. Specifically, the manager will immediately fail if the number
+// of tasks stopped for a group ever exceeds the number of tasks started for
+// that group. Clients are responsible for namespacing their group strings
+// properly. All methods must be called on the UI thread.
+@interface CRWNetworkActivityIndicatorManager : NSObject
+
+// Returns the singleton CRWNetworkActivityIndicatorManager.
++ (CRWNetworkActivityIndicatorManager*)sharedInstance;
+
+// Begins a single network task. The network activity indicator is guaranteed
+// to be shown after this finishes (if it isn't already). |group| must be
+// non-nil.
+- (void)startNetworkTaskForGroup:(NSString*)group;
+
+// Stops a single network task. The network activity indicator may or may not
+// stop being shown once this finishes, depending on whether there are other
+// unstopped tasks or not. |group| must be non-nil, and have at least one
+// unstopped task.
+- (void)stopNetworkTaskForGroup:(NSString*)group;
+
+// A convenience method for starting multiple network tasks at once. |group|
+// must be non-nil. |numTasks| must be greater than 0.
+- (void)startNetworkTasks:(NSUInteger)numTasks forGroup:(NSString*)group;
+
+// A convenience method for stopping multiple network tasks at once. |group|
+// must be non-nil. |numTasks| must be greater than 0, and |numTasks| must be
+// less than or equal to the number of unstopped tasks in |group|.
+- (void)stopNetworkTasks:(NSUInteger)numTasks forGroup:(NSString*)group;
+
+// A convenience method for stopping all network tasks for a group. |group|
+// must be non-nil. Can be called on any group at any time, regardless of
+// whether the group has any unstopped network tasks or not. Returns the number
+// of tasks stopped by this call.
+- (NSUInteger)clearNetworkTasksForGroup:(NSString*)group;
+
+// Returns the number of unstopped network tasks for |group|. |group| must be
+// non-nil. Can be called on any group at any time, regardless of whether the
+// group has any unstopped network tasks or not.
+- (NSUInteger)numNetworkTasksForGroup:(NSString*)group;
+
+// Returns the total number of unstopped network tasks, across all groups. This
+// method was added for testing only. Clients should never depend on this, and
+// should instead only be concerned with the number of unstopped network tasks
+// for the groups they control, which can be queried using
+// |-numNetworkTasksForGroup:|.
+- (NSUInteger)numTotalNetworkTasks;
+
+@end
+
+#endif  // IOS_WEB_CRW_NETWORK_ACTIVITY_INDICATOR_MANAGER_H_