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)
+            return uaString;
+        console.assert(uaString.indexOf("%s") === uaString.lastIndexOf("%s"), "User agent string contains multiple %s");
+        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"

[dgozman, 2016/09/02 23:42:45]

I think doesn't work for content shell. Can we generalize it?

[luoe, 2016/09/03 00:08:15]

Can you show me how this breaks?

I patched a branch from today, built content_shell, and it seems to extract the
"99.77.34.5" out of "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML,
like Gecko) Chrome/99.77.34.5 Safari/537.36".

[dgozman, 2016/09/03 01:17:42]

I was thinking that content shell has different UA string. My bad.

Since we don't run frontend in other browsers, this is fine for now, but I'd
actually prefer to generate some constants at a build time instead of adding so
much code here. WDYT?

+        if (!sectionName || sectionName.indexOf("/") !== -1)
+            return WebInspector.BrowserVersionInfo._defaultVersion(sectionName);
+        var userAgent = navigator.userAgent;
+        var sectionRegex = new RegExp("(?:^|[^\\w])" + sectionName.escapeForRegExp() + "/([^\\s]+)");

[allada, 2016/09/02 23:48:29]

nit: lets use "(?:^|\\W)" and "/(\\S+)"

[luoe, 2016/09/03 00:08:14]

Done.

+        var sectionMatch = userAgent.match(sectionRegex);
+        if (!sectionMatch || 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;
+    }
+};