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

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

Index: chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabsConnectionTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabsConnectionTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabsConnectionTest.java
index 96d4bc8667cd78c36fc07ce887d86f83ec89e448..2a1179e030aba5b1ff6b90bcf9515177851f5b37 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabsConnectionTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/customtabs/CustomTabsConnectionTest.java
@@ -160,13 +160,13 @@ public class CustomTabsConnectionTest {
         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());
             }
         });
     }
@@ -357,9 +357,10 @@ public class CustomTabsConnectionTest {
         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() {
@@ -635,4 +636,52 @@ public class CustomTabsConnectionTest {
             });
         }
     }
+
+    @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());
+            }
+        });
+    }
 }