Speculative deflake testCreateAndGcManyTimes

Suspicion is the single gc call did not kill off a AwContents due to
transient internal strong refs during load. Suspect this is the problem
due to logcat being completely empty for the 15 seconds when the poll
at the end of the test happens.

BUG=469803

Review URL: https://codereview.chromium.org/1039873004

Cr-Commit-Position: refs/heads/master@{#323159}

1 files changed, 32 insertions, 4 deletions

diff --git a/android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java b/android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java
index 0478a00..fa4bfd0 100644
--- a/android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java
+++ b/android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java
@@ -19,6 +19,8 @@ import android.view.KeyEvent;
 import android.view.View;
 import android.webkit.JavascriptInterface;
 
+import static org.chromium.base.test.util.ScalableTimeout.scaleTimeout;
+
 import org.apache.http.Header;
 import org.apache.http.HttpRequest;
 import org.chromium.android_webview.AwContents;
@@ -29,6 +31,8 @@ import org.chromium.base.annotations.SuppressFBWarnings;
 import org.chromium.base.test.util.Feature;
 import org.chromium.base.test.util.MinAndroidSdkLevel;
 import org.chromium.content.browser.test.util.CallbackHelper;
+import org.chromium.content.browser.test.util.Criteria;
+import org.chromium.content.browser.test.util.CriteriaHelper;
 import org.chromium.content_public.browser.LoadUrlParams;
 import org.chromium.net.test.util.TestWebServer;
 
@@ -188,12 +192,36 @@ public class AwContentsTest extends AwTestBase {
 
         Runtime.getRuntime().gc();
 
-        pollOnUiThread(new Callable<Boolean>() {
+        Criteria criteria = new Criteria() {
             @Override
-            public Boolean call() {
-                return AwContents.getNativeInstanceCount() <= maxIdleInstances;
+            public boolean isSatisfied() {
+                try {
+                    return runTestOnUiThreadAndGetResult(new Callable<Boolean>() {
+                        @Override
+                        public Boolean call() {
+                            return AwContents.getNativeInstanceCount() <= maxIdleInstances;
+                        }
+                    });
+                } catch (Exception e) {
+                    return false;
+                }
             }
-        });
+        };
+
+        // Depending on a single gc call can make this test flaky. It's possible
+        // that the WebView still has transient references during load so it does not get
+        // gc-ed in the one gc-call above. Instead call gc again if exit criteria fails to
+        // catch this case.
+        final long timeoutBetweenGcMs = scaleTimeout(1000);
+        for (int i = 0; i < 15; ++i) {
+            if (CriteriaHelper.pollForCriteria(criteria, timeoutBetweenGcMs, CHECK_INTERVAL)) {
+                break;
+            } else {
+                Runtime.getRuntime().gc();
+            }
+        }
+
+        assertTrue(criteria.isSatisfied());
     }
 
     @SmallTest