tools: Extend the CustomTabs benchmark scripts to speculative_prefetch.

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java

Index: chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
index c0c7e0cb84be6a61c19968ec13015d7bf16552ea..99fb999e82a531c22642077622bc607d40ad8bb4 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
@@ -77,6 +77,7 @@ public class CustomTabsConnection {
     @VisibleForTesting
     static final String DEBUG_OVERRIDE_KEY =
             "android.support.customtabs.maylaunchurl.DEBUG_OVERRIDE";
+    private static final int NO_OVERRIDE = 0;
     @VisibleForTesting
     static final int NO_PRERENDERING = 1;
     @VisibleForTesting
@@ -276,7 +277,8 @@ public class CustomTabsConnection {
         Profile profile = Profile.getLastUsedProfile();
 
         url = DataReductionProxySettings.getInstance().maybeRewriteWebliteUrl(url);
-        int debugOverrideValue = extras != null ? extras.getInt(DEBUG_OVERRIDE_KEY, -1) : -1;
+        int debugOverrideValue = NO_OVERRIDE;
+        if (extras != null) debugOverrideValue = extras.getInt(DEBUG_OVERRIDE_KEY, NO_OVERRIDE);
 
         boolean didStartPrerender = false, didStartPrefetch = false;
         boolean mayPrerender = mayPrerender(session);