Upstream various ios/web utilities and helpers

ios/web/net/request_group_util.h

Index: ios/web/net/request_group_util.h
diff --git a/ios/web/net/request_group_util.h b/ios/web/net/request_group_util.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_NET_REQUEST_GROUP_UTIL_H_
+#define IOS_WEB_NET_REQUEST_GROUP_UTIL_H_
+
+@class NSString;
+@class NSURL;
+@class NSURLRequest;
+
+// Request group IDs are internally used by the web layer to associate network
+// requests to RequestTracker instances, and in turn, to WebState instances.
+// The ID can be added to the user-agent string by UIWebView in most cases and
+// then extracted by the network layer.
+// However, when using non-standard schemes, UIWebView does not add the
+// "User-Agent" HTTP header to the requests. The workaround for this case is to
+// add the ID directly in the URL of the main request (which is the only request
+// accessible from the UIWebView delegate).
+
+namespace web {
+
+// Generates a request-group ID.
+NSString* GenerateNewRequestGroupID();
+
+// Extracts the requestGroupID embedded in a User-Agent string or nil if a
+// requestGroupID cannot be located.
+NSString* ExtractRequestGroupIDFromUserAgent(NSString* user_agent);
+
+// Returns a new user agent, which is the result of the encoding of
+// |request_group_id| in |base_user_agent|. The request group ID can be later
+// extracted with ExtractRequestGroupIDFromUserAgent().
+NSString* AddRequestGroupIDToUserAgent(NSString* base_user_agent,
+                                       NSString* request_group_id);
+
+// Extracts the requestGroupID embedded in a NSURL or nil if a requestGroupID
+// cannot be located.
+NSString* ExtractRequestGroupIDFromURL(NSURL* url);
+
+// Returns a new user agent, which is the result of the encoding of
+// |request_group_id| in |base_url|. The request group ID can be later extracted
+// with ExtractRequestGroupIDFromURL().
+NSURL* AddRequestGroupIDToURL(NSURL* base_url, NSString* request_group_id);
+
+// Extracts the request group ID from |request| by retrieving it from the
+// user-agent if possible, and from the parent URL otherwise.
+// The ID can only be retrived from the parent URL if its scheme is
+// |application_scheme|.
+// The reason why the |application_scheme| case is different is because
+// UIWebView does not provide a "User-Agent" HTTP header for these requests.
+// The ID is then encoded in the URL of the main request, and thus sub-requests
+// have to look in their parent URL for the ID.
+NSString* ExtractRequestGroupIDFromRequest(NSURLRequest* request,
+                                           NSString* application_scheme);
+
+}  // namespace web
+
+#endif  // IOS_WEB_NET_REQUEST_GROUP_UTIL_H_