Treat unknown accounts as auth errors in tests

We have multiple flaky tests that complain with:
java.lang.IllegalArgumentException: Can not find AccountHolder for account Account {name=test@gmail.com, type=com.google}
    at org.chromium.components.signin.test.util.FakeAccountManagerDelegate.getAccountHolder(FakeAccountManagerDelegate.java:341)
    at org.chromium.components.signin.test.util.FakeAccountManagerDelegate.getAuthToken(FakeAccountManagerDelegate.java:259)
    at org.chromium.components.signin.AccountManagerFacade$3.run(AccountManagerFacade.java:492)
    at org.chromium.components.signin.AccountManagerFacade$3.run(AccountManagerFacade.java:489)
    at org.chromium.components.signin.AccountManagerFacade$ConnectionRetry$1.doInBackground(AccountManagerFacade.java:829)
    at org.chromium.base.task.AsyncTask$1.call(AsyncTask.java:99)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    ... 3 more

One hypothesis is that GetAccountHolder() fails during teardown of the
test. Hence, let's treat it as auth error such that
AccountManagerFacade.getAuthToken() treats it as a regular failed
attempt (but doesn't necessarily make the test fail).

Bug: 879246
Change-Id: I47c69af1af2579ec70ece468e6701f67ef065992
Reviewed-on: https://chromium-review.googlesource.com/c/1264678Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597586}

components/signin/core/browser/android/java/src/org/chromium/components/signin/AuthException.java

@@ -37,6 +37,17 @@ public class AuthException extends Exception {
         mIsTransientError = isTransientError;
     }
 
+    /**
+     * Constructs an instance without a wrapped exception, based on transience flag and message.
+     * @param isTransientError Whether the error is transient and we can retry.
+     *         Use {@link #TRANSIENT} and {@link #NONTRANSIENT} for readability.
+     * @param message Message describing context in which auth failure happened.
+     */
+    public AuthException(boolean isTransientError, String message) {
+        super(message);
+        mIsTransientError = isTransientError;
+    }
+
     /**
      * @return Whether the error is transient and we can retry.
      */

components/signin/core/browser/android/javatests/src/org/chromium/components/signin/test/util/FakeAccountManagerDelegate.java

@@ -21,6 +21,7 @@ import org.chromium.components.signin.AccountManagerDelegate;
 import org.chromium.components.signin.AccountManagerDelegateException;
 import org.chromium.components.signin.AccountManagerFacade;
 import org.chromium.components.signin.AccountsChangeObserver;
+import org.chromium.components.signin.AuthException;
 import org.chromium.components.signin.ProfileDataSource;
 
 import java.lang.annotation.Retention;
@@ -255,8 +256,12 @@ public class FakeAccountManagerDelegate implements AccountManagerDelegate {
     }
 
     @Override
-    public String getAuthToken(Account account, String authTokenScope) {
-        AccountHolder ah = getAccountHolder(account);
+    public String getAuthToken(Account account, String authTokenScope) throws AuthException {
+        AccountHolder ah = tryGetAccountHolder(account);
+        if (ah == null) {
+            throw new AuthException(AuthException.NONTRANSIENT,
+                    "Cannot get auth token for unknown account '" + account + "'");
+        }
         assert ah.hasBeenAccepted(authTokenScope);
         synchronized (mAccounts) {
             // Some tests register auth tokens with value null, and those should be preserved.
@@ -327,7 +332,7 @@ public class FakeAccountManagerDelegate implements AccountManagerDelegate {
         ThreadUtils.postOnUiThread(() -> callback.onResult(true));
     }
 
-    private AccountHolder getAccountHolder(Account account) {
+    private AccountHolder tryGetAccountHolder(Account account) {
         if (account == null) {
             throw new IllegalArgumentException("Account can not be null");
         }
@@ -338,6 +343,14 @@ public class FakeAccountManagerDelegate implements AccountManagerDelegate {
                 }
             }
         }
-        throw new IllegalArgumentException("Can not find AccountHolder for account " + account);
+        return null;
+    }
+
+    private AccountHolder getAccountHolder(Account account) {
+        AccountHolder ah = tryGetAccountHolder(account);
+        if (ah == null) {
+            throw new IllegalArgumentException("Can not find AccountHolder for account " + account);
+        }
+        return ah;
     }
 }