Merge "Add `auth-link` frontend extension point"

Documentation/pg-plugin-endpoints.txt

diff --git a/Documentation/pg-plugin-endpoints.txt b/Documentation/pg-plugin-endpoints.txt
index dd82f27..967946d 100644
--- a/Documentation/pg-plugin-endpoints.txt
+++ b/Documentation/pg-plugin-endpoints.txt
@@ -43,6 +43,11 @@
 
 The following endpoints are available to plugins.
 
+=== auth-link
+The `auth-link` extension point is located in the top right corner of anonymous
+pages. The purpose is to improve user experience for custom OAuth providers by
+providing custom components and/or visual feedback of authentication progress.
+
 === banner
 The `banner` extension point is located at the top of all pages. The purpose
 is to allow plugins to show outage information and important announcements to

polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts

diff --git a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts
index be94050..a55173c 100644
--- a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts
+++ b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts
@@ -437,7 +437,9 @@
           ></gr-icon>
         </div>
         ${this.renderRegister()}
-        <a class="loginButton" href=${this.loginUrl}>${this.loginText}</a>
+        <gr-endpoint-decorator name="auth-link">
+          <a class="loginButton" href=${this.loginUrl}>${this.loginText}</a>
+        </gr-endpoint-decorator>
         <a
           class="settingsButton"
           href="${getBaseUrl()}/settings/"

polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts

diff --git a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts
index d2b833f..4b9c313 100644
--- a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts
+++ b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts
@@ -82,7 +82,9 @@
               >
               </gr-icon>
             </div>
-            <a class="loginButton" href="/login"> Sign in </a>
+            <gr-endpoint-decorator name="auth-link">
+              <a class="loginButton" href="/login"> Sign in </a>
+            </gr-endpoint-decorator>
             <a
               aria-label="Settings"
               class="settingsButton"