customtabs: Add a flag to mayLaunchUrl() to force prefetch.

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 7a0f152006aff7cc27cfb084a47a4cfebc60ce72..b1008a9384b5033d25c76aee45ff96e882180b97 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
@@ -189,7 +189,8 @@ public class CustomTabsConnectionTest extends InstrumentationTestCase {
         assertTrue(mCustomTabsConnection.newSession(token));
 
         Bundle extras = new Bundle();
-        extras.putBoolean(CustomTabsConnection.NO_PRERENDERING_KEY, true);
+        extras.putInt(
+                CustomTabsConnection.DEBUG_OVERRIDE_KEY, CustomTabsConnection.NO_PRERENDERING);
         assertTrue(mCustomTabsConnection.mayLaunchUrl(token, Uri.parse(URL), extras, null));
 
         ThreadUtils.runOnUiThreadBlocking(new Runnable() {
@@ -303,6 +304,26 @@ public class CustomTabsConnectionTest extends InstrumentationTestCase {
 
     @SmallTest
     @Restriction(RESTRICTION_TYPE_NON_LOW_END_DEVICE)
+    public void testPrefetchOnlyNoPrerenderHasSpareWebContents() {
+        assertTrue(mCustomTabsConnection.warmup(0));
+        final CustomTabsSessionToken token =
+                CustomTabsSessionToken.createDummySessionTokenForTesting();
+        assertTrue(mCustomTabsConnection.newSession(token));
+
+        Bundle extras = new Bundle();
+        extras.putInt(CustomTabsConnection.DEBUG_OVERRIDE_KEY, CustomTabsConnection.PREFETCH_ONLY);
+        assertTrue(mCustomTabsConnection.mayLaunchUrl(token, Uri.parse(URL), extras, null));
+
+        ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+            @Override
+            public void run() {
+                assertSpareWebContentsNotNullAndDestroy();
+            }
+        });
+    }
+
+    @SmallTest
+    @Restriction(RESTRICTION_TYPE_NON_LOW_END_DEVICE)
     @RetryOnFailure
     public void testCanCancelPrerender() {
         final CustomTabsSessionToken token = assertWarmupAndMayLaunchUrl(null, URL, true);