[WebDriver BiDi] emulate user-agent string

# Conflicts:
#	source

Author: sadym-chromium

source

@@ -4645,6 +4645,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li><dfn data-x="navigation-status-complete" data-x-href="https://w3c.github.io/webdriver-bidi/#navigation-status-complete">navigation status complete</dfn></li>
      <li><dfn data-x="navigation-status-url" data-x-href="https://w3c.github.io/webdriver-bidi/#navigation-status-url">navigation status url</dfn></li>
      <li><dfn data-x="navigation-status-suggested-filename" data-x-href="https://w3c.github.io/webdriver-bidi/#navigation-status-suggested-filename">navigation status suggested filename</dfn></li>
+     <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-emulated-user-agent">WebDriver BiDi emulated User-Agent</dfn></li>
      <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigation-aborted">WebDriver BiDi navigation aborted</dfn></li>
      <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigation-committed">WebDriver BiDi navigation committed</dfn></li>
      <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigation-failed">WebDriver BiDi navigation failed</dfn></li>
@@ -121071,12 +121072,12 @@ interface <dfn interface>Navigator</dfn> {
   data-x="dom-navigator-appVersion">appVersion</code></dfn> getter steps are:</p>
 
   <ol>
-   <li><p>If the <span data-x="default-user-agent-value">default `<code>User-Agent</code>`
-   value</span> does not start with `<code data-x="">Mozilla/5.0 (</code>`, then return the empty
-   string.</p></li>
+   <li>Let <var>userAgent</var> be <span data-x="dom-navigator-userAgent">userAgent</span>.</li>
+
+   <li><p>If the <var>userAgent</var> does not start with `<code data-x="">Mozilla/5.0 (</code>`,
+   then return the empty string.</p></li>
 
-   <li><p>Let <var>trail</var> be the substring of the <span
-   data-x="default-user-agent-value">default `<code>User-Agent</code>` value</span>, <span
+   <li><p>Let <var>trail</var> be the substring of the <var>userAgent</var>, <span
    data-x="isomorphic decode">isomorphic decoded</span>, that follows the "<code
    data-x="">Mozilla/</code>" prefix.</p></li>
 
@@ -121126,8 +121127,18 @@ interface <dfn interface>Navigator</dfn> {
    </dl>
 
   <p>The <dfn attribute for="NavigatorID"><code data-x="dom-navigator-userAgent">userAgent</code></dfn>
-  getter steps are to return the <span data-x="default-user-agent-value">default `<code>User-Agent</code>`
-  value</span>.</p>
+  getter steps are:</p>
+
+  <ol>
+    <li><p>Let <var>emulatedUserAgent</var> be the result of <span>WebDriver BiDi emulated
+    User-Agent</span> with <span>this</span>'s <span>relevant settings object</span>.</p></li>
+
+    <li><p>If <var>emulatedUserAgent</var> is not null, then return
+    <var>emulatedUserAgent</var>.</p></li>
+
+    <li><p>Return <span data-x="default-user-agent-value">default `<code>User-Agent</code>`
+    value</span>.</p></li>
+  </ol>
 
   <p>The <dfn attribute for="NavigatorID"><code data-x="dom-navigator-vendor">vendor</code></dfn>
   getter steps are to return the appropriate string from the following list:</p>