Fix tests calling methods on the wrong thread.

chrome/android/javatests/src/org/chromium/chrome/browser/ChromeBackupIntegrationTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/ChromeBackupIntegrationTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/ChromeBackupIntegrationTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/ChromeBackupIntegrationTest.java
index 9d86669ee071cf84e7a8a8afe8283209d2d0f74a..469e20900762e4e76b8991cf42ac18d78fb8ef4c 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/ChromeBackupIntegrationTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/ChromeBackupIntegrationTest.java
@@ -13,6 +13,7 @@ import android.test.suitebuilder.annotation.SmallTest;
 
 import org.chromium.base.ContextUtils;
 import org.chromium.base.StreamUtil;
+import org.chromium.base.ThreadUtils;
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.MinAndroidSdkLevel;
 import org.chromium.chrome.browser.firstrun.FirstRunSignInProcessor;
@@ -91,7 +92,13 @@ public class ChromeBackupIntegrationTest extends ChromeTabbedActivityTestBase {
         MockAccountManager accountManager =
                 new MockAccountManager(mTargetContext, getInstrumentation().getContext(), account);
         AccountManagerHelper.overrideAccountManagerHelperForTests(mTargetContext, accountManager);
-        AccountIdProvider.setInstanceForTest(new MockAccountIdProvider());
+
+        ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+            @Override
+            public void run() {
+                AccountIdProvider.setInstanceForTest(new MockAccountIdProvider());
+            }
+        });
     }
 
     @SmallTest