customtabs: Re-Create a spare renderer on Tab close.

chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java
index 11399477672866f4e1742ae5c1d0f4f5605c3aa9..29f1f048abb2e30e6db6e1e71c9a88b5e70c7683 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabActivityTest.java
@@ -54,6 +54,7 @@ import org.chromium.chrome.browser.ChromeSwitches;
 import org.chromium.chrome.browser.ChromeTabbedActivity;
 import org.chromium.chrome.browser.IntentHandler;
 import org.chromium.chrome.browser.TabsOpenedFromExternalAppTest;
+import org.chromium.chrome.browser.WarmupManager;
 import org.chromium.chrome.browser.appmenu.AppMenuHandler;
 import org.chromium.chrome.browser.document.ChromeLauncherActivity;
 import org.chromium.chrome.browser.metrics.PageLoadMetrics;
@@ -1146,6 +1147,35 @@ public class CustomTabActivityTest extends CustomTabActivityTestBase {
         });
     }
 
+    @SmallTest
+    @Restriction(RESTRICTION_TYPE_NON_LOW_END_DEVICE)
+    public void testRecreateSpareRendererOnTabClose() throws Exception {
+        Context context = getInstrumentation().getTargetContext().getApplicationContext();
+        warmUpAndWait();
+
+        try {
+            startCustomTabActivityWithIntent(
+                    CustomTabsTestUtils.createMinimalCustomTabIntent(context, mTestPage));
+        } catch (InterruptedException e) {
+            fail();
+        }
+
+        ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+            @Override
+            public void run() {
+                assertFalse(WarmupManager.getInstance().hasSpareWebContents());
+                final CustomTabActivity activity = (CustomTabActivity) getActivity();
+                activity.finishAndClose(false);
+            }
+        });
+        CriteriaHelper.pollUiThread(new Criteria("No new spare renderer") {
+            @Override
+            public boolean isSatisfied() {
+                return WarmupManager.getInstance().hasSpareWebContents();
+            }
+        }, 2000, 200);
+    }
+
     /**
      * Tests that prerendering accepts a referrer, and that this is not lost when launching the
      * Custom Tab.