customtabs: Don't always destroy the spare WebContents before prerender.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.customtabs;
 
 import static org.chromium.base.test.util.Restriction.RESTRICTION_TYPE_NON_LOW_END_DEVICE;
 
 import android.app.Application;
 import android.content.Context;
@@ skipping 142 matching lines @@
 
     @Test
     @SmallTest
     @Restriction(RESTRICTION_TYPE_NON_LOW_END_DEVICE)
     public void testPrerenderDestroysSpareRenderer() {
         CustomTabsConnection.getInstance((Application) mAppContext).setForcePrerender(true);
         final CustomTabsSessionToken token = assertWarmupAndMayLaunchUrl(null, URL, true);
         ThreadUtils.runOnUiThreadBlocking(new Runnable() {
             @Override
             public void run() {
-                Assert.assertFalse(WarmupManager.getInstance().hasSpareWebContents());
                 String referrer =
                         mCustomTabsConnection.getReferrerForSession(token).getUrl();
                 WebContents webContents =
                         mCustomTabsConnection.takePrerenderedUrl(token, URL, referrer);
                 Assert.assertNotNull(webContents);
                 webContents.destroy();
+                Assert.assertFalse(WarmupManager.getInstance().hasSpareWebContents());
             }
         });
     }
 
     /*
      * Tests that when the disconnection notification comes from a non-UI thread, Chrome doesn't
      * crash. Non-regression test for crbug.com/623128.
      */
     @Test
     @SmallTest
@@ skipping 170 matching lines @@
     @Test
     @SmallTest
     @Restriction(RESTRICTION_TYPE_NON_LOW_END_DEVICE)
     @RetryOnFailure
     public void testCanCancelPrerender() {
         CustomTabsConnection.getInstance((Application) mAppContext).setForcePrerender(true);
         final CustomTabsSessionToken token = assertWarmupAndMayLaunchUrl(null, URL, true);
         ThreadUtils.runOnUiThreadBlocking(new Runnable() {
             @Override
             public void run() {
-                Assert.assertNull(WarmupManager.getInstance().takeSpareWebContents(false, false));
+                Assert.assertEquals(URL, mCustomTabsConnection.getSpeculatedUrl(token));
             }
         });
+
         Assert.assertTrue(mCustomTabsConnection.mayLaunchUrl(token, null, null, null));
         // mayLaunchUrl() posts a task, the following has to run after it.
         ThreadUtils.runOnUiThreadBlocking(new Runnable() {
             @Override
             public void run() {
                 String referrer = mCustomTabsConnection.getReferrerForSession(token).getUrl();
                 Assert.assertNull(mCustomTabsConnection.takePrerenderedUrl(token, URL, referrer));
             }
         });
     }
@@ skipping 255 matching lines @@
             });
         } finally {
             ThreadUtils.runOnUiThreadBlocking(new Runnable() {
                 @Override
                 public void run() {
                     PrefServiceBridge.getInstance().setNetworkPredictionEnabled(enabled);
                 }
             });
         }
     }
+
+    @Test
+    @SmallTest
+    @Restriction(RESTRICTION_TYPE_NON_LOW_END_DEVICE)
+    public void testCellularPrerenderingDoesntKillSpareRenderer() throws Exception {
+        final CustomTabsSessionToken token =
+                CustomTabsSessionToken.createDummySessionTokenForTesting();
+        Assert.assertTrue(mCustomTabsConnection.newSession(token));
+        mCustomTabsConnection.setShouldPrerenderOnCellularForSession(token, true);
+        mCustomTabsConnection.warmup(0);
+
+        Assert.assertTrue(mCustomTabsConnection.mayLaunchUrl(token, Uri.parse(URL), null, null));
+        ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+            @Override
+            public void run() {
+                Assert.assertTrue(WarmupManager.getInstance().hasSpareWebContents());
+                String referrer = mCustomTabsConnection.getReferrerForSession(token).getUrl();
+                WebContents webContents =
+                        mCustomTabsConnection.takePrerenderedUrl(token, URL, referrer);
+                Assert.assertNotNull(webContents);
+                webContents.destroy();
+                // destroyed when the prerender is used.
+                Assert.assertFalse(WarmupManager.getInstance().hasSpareWebContents());
+            }
+        });
+    }
+
+    @Test
+    @SmallTest
+    @Restriction(RESTRICTION_TYPE_NON_LOW_END_DEVICE)
+    public void testUnmatchedCellularPrerenderingDoesntKillSpareRenderer() throws Exception {
+        final CustomTabsSessionToken token =
+                CustomTabsSessionToken.createDummySessionTokenForTesting();
+        Assert.assertTrue(mCustomTabsConnection.newSession(token));
+        mCustomTabsConnection.setShouldPrerenderOnCellularForSession(token, true);
+        mCustomTabsConnection.warmup(0);
+
+        Assert.assertTrue(mCustomTabsConnection.mayLaunchUrl(token, Uri.parse(URL), null, null));
+        ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+            @Override
+            public void run() {
+                Assert.assertTrue(WarmupManager.getInstance().hasSpareWebContents());
+                String referrer = mCustomTabsConnection.getReferrerForSession(token).getUrl();
+                Assert.assertNull(mCustomTabsConnection.takePrerenderedUrl(token, URL2, referrer));
+                Assert.assertTrue(WarmupManager.getInstance().hasSpareWebContents());
+            }
+        });
+    }
 }