DevTools: patch browser's Chrome version into Chrome user agents for emulation

third_party/WebKit/Source/devtools/front_end/common/BrowserVersionInfo.js

+// 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.
+
+WebInspector.BrowserVersionInfo = {
+    DefaultChromeVersion: "54.0.2834.0",
+
+    /**
+     * @param {string} uaString
+     * @param {string} sectionName
+     * @return {string}
+     */
+    patchUserAgentWithCurrentVersion: function(uaString, sectionName)
+    {
+        var currentVersion = WebInspector.BrowserVersionInfo._getVersion(sectionName);
+        if (!currentVersion || uaString.indexOf("%s") === -1)

[allada, 2016/09/02 21:08:05]

Can we add a test to make sure if a user adds a custom user agent with %s in it,
it will not change their user agent?

[luoe, 2016/09/02 23:08:09]

Done.

+            return uaString;
+        return String.sprintf(uaString, currentVersion);
+    },
+
+    /**
+     * @param {string} sectionName
+     * @return {?string}
+     */
+    _getVersion: function(sectionName)
+    {
+        // Extracts a version string from navigator.userAgent
+        // e.g. _getVersion("Chrome") === "1.2.3.4" when user agent is: "Chrome/1.2.3.4"
+        if (!sectionName || sectionName.indexOf("/") !== -1)
+            return WebInspector.BrowserVersionInfo._defaultVersion(sectionName);
+        var userAgent = navigator.userAgent;
+        var sectionRegex = new RegExp("(?:^|[^\\w])" + sectionName + "/([^\\s]+)");

[allada, 2016/09/02 21:08:05]

var sectionRegex = new RegExp("(?:^|[^\\w])" + sectionName.escapeForRegExp() +
"/([^\\s]+)", "ig");

I assume we should replace all instances of "Chrome/" and make it case
insensitive?

[luoe, 2016/09/02 23:08:09]

escapeForRegExp: done
This function just wants to extract THE value associated with "Chrome/", so I
just want the one "Chrome/", no need for "ig" flags.  

+        var sectionMatch = userAgent.match(sectionRegex);
+        if (sectionMatch.length < 2)
+            return WebInspector.BrowserVersionInfo._defaultVersion(sectionName);
+        return sectionMatch[1];
+    },
+
+    /**
+     * @param {string} sectionName
+     * @return {?string}
+     */
+    _defaultVersion: function(sectionName)
+    {
+        if (sectionName === "Chrome")
+            return WebInspector.BrowserVersionInfo.DefaultChromeVersion;
+        return null;
+    }
+};