Remove 10.13, 10.14 support from auth session handling

These macOS releases are no longer supported by Chromium.

Bug: 1410851
Change-Id: I4cfdd65d59bfba700033b217b2d3337ec10e7130
Cq-Include-Trybots: luci.chrome.try:mac-chrome
Validate-Test-Flakiness: skip
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4672397
Auto-Submit: Avi Drissman <avi@chromium.org>
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Code-Coverage: Findit <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Leonard Grey <lgrey@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1168712}

chrome/browser/mac/auth_session_request.h

@@ -28,7 +28,7 @@ class Profile;
 
 // A class to manage the WebContents running an
 // ASWebAuthenticationSessionRequest.
-class API_AVAILABLE(macos(10.15)) AuthSessionRequest
+class AuthSessionRequest
     : public content::WebContentsObserver,
       public content::WebContentsUserData<AuthSessionRequest> {
  public:
@@ -102,6 +102,6 @@ class API_AVAILABLE(macos(10.15)) AuthSessionRequest
 // If there is an authentication session in progress for the given navigation
 // handle, install a throttle.
 std::unique_ptr<content::NavigationThrottle> MaybeCreateAuthSessionThrottleFor(
-    content::NavigationHandle* handle) API_AVAILABLE(macos(10.15));
+    content::NavigationHandle* handle);
 
 #endif  // CHROME_BROWSER_MAC_AUTH_SESSION_REQUEST_H_

chrome/browser/mac/auth_session_request.mm

@@ -350,7 +350,7 @@ ThrottleCheckResult HandleRequest() {
 WEB_CONTENTS_USER_DATA_KEY_IMPL(AuthSessionRequest);
 
 std::unique_ptr<content::NavigationThrottle> MaybeCreateAuthSessionThrottleFor(
-    content::NavigationHandle* handle) API_AVAILABLE(macos(10.15)) {
+    content::NavigationHandle* handle) {
   AuthSessionRequest* request =
       AuthSessionRequest::FromWebContents(handle->GetWebContents());
   if (!request)