Log initialization errors in JUnit test suites.

This helps with debugging, as the thrown exception will get mangled by
the test runner script.

Bug: 807237
Change-Id: I74677e491c0115521b9b79c051f5213e832545ae
Reviewed-on: https://chromium-review.googlesource.com/892863Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Bernhard Bauer <bauerb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532862}

base/test/android/javatests/src/org/chromium/base/test/BaseJUnit4ClassRunner.java

@@ -19,6 +19,7 @@ import org.junit.runners.model.Statement;
 
 import org.chromium.base.CollectionUtil;
 import org.chromium.base.CommandLine;
+import org.chromium.base.Log;
 import org.chromium.base.test.BaseTestResult.PreTestHook;
 import org.chromium.base.test.util.DisableIfSkipCheck;
 import org.chromium.base.test.util.MinAndroidSdkLevelSkipCheck;
@@ -39,6 +40,7 @@ import java.util.List;
  *  and {@link #isIgnored} to add SkipChecks and PreTesthook.
  */
 public class BaseJUnit4ClassRunner extends AndroidJUnit4ClassRunner {
+    private static final String TAG = "BaseJUnit4ClassRunnr";
     private final List<SkipCheck> mSkipChecks;
     private final List<PreTestHook> mPreTestHooks;
 
@@ -127,6 +129,16 @@ public class BaseJUnit4ClassRunner extends AndroidJUnit4ClassRunner {
         return l;
     }
 
+    @Override
+    protected void collectInitializationErrors(List<Throwable> errors) {
+        super.collectInitializationErrors(errors);
+        // Log any initialization errors to help debugging, as the host-side test runner can get
+        // confused by the thrown exception.
+        if (!errors.isEmpty()) {
+            Log.e(TAG, "Initialization errors in %s: %s", getTestClass().getName(), errors);
+        }
+    }
+
     /**
      * Change this static function to add or take out default {@code SkipCheck}s.
      */