[TTS] Default-enable AMP clicks promote to new tab

A previous CL added special treatment for AMP pages when they
are clicked on in the Contextual Search Overlay.  However the
functionality was behind a flag, which we never enabled.

This changes the AMP case to be behind a default-enabled flag that
will allow us to disable if needed.

BUG=645325

Review-Url: https://codereview.chromium.org/2714623002
Cr-Commit-Position: refs/heads/master@{#453291}
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchFieldTrial.java b/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchFieldTrial.java
index a9866ba..20d43e1 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchFieldTrial.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchFieldTrial.java
@@ -81,7 +81,7 @@
     @VisibleForTesting
     static final String ONLINE_DETECTION_DISABLED = "disable_online_detection";
 
-    private static final String ENABLE_AMP_AS_SEPARATE_TAB = "enable_amp_as_separate_tab";
+    private static final String DISABLE_AMP_AS_SEPARATE_TAB = "disable_amp_as_separate_tab";
 
     // Privacy-related flags
     private static final String ENABLE_SEND_HOME_COUNTRY = "enable_send_home_country";
@@ -109,7 +109,7 @@
     private static Boolean sShouldHideContextualCardsData;
     private static Boolean sIsContextualCardsBarIntegrationEnabled;
     private static Boolean sIsOnlineDetectionDisabled;
-    private static Boolean sIsAmpAsSeparateTabEnabled;
+    private static Boolean sIsAmpAsSeparateTabDisabled;
     private static Boolean sContextualSearchSingleActionsEnabled;
     private static Boolean sCanSendHomeCountry;
     private static Boolean sContextualSearchUrlActionsEnabled;
@@ -367,13 +367,13 @@
     }
 
     /**
-     * @return Whether to auto-promote clicks in the AMP carousel into a separate Tab.
+     * @return Whether to disable auto-promotion of clicks in the AMP carousel into a separate Tab.
      */
-    static boolean isAmpAsSeparateTabEnabled() {
-        if (sIsAmpAsSeparateTabEnabled == null) {
-            sIsAmpAsSeparateTabEnabled = getBooleanParam(ENABLE_AMP_AS_SEPARATE_TAB);
+    static boolean isAmpAsSeparateTabDisabled() {
+        if (sIsAmpAsSeparateTabDisabled == null) {
+            sIsAmpAsSeparateTabDisabled = getBooleanParam(DISABLE_AMP_AS_SEPARATE_TAB);
         }
-        return sIsAmpAsSeparateTabEnabled;
+        return sIsAmpAsSeparateTabDisabled;
     }
 
     // TODO(donnd): Remove once bar-integration is fully landed if still unused (native only).
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchManager.java b/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchManager.java
index b32f4967..74383743 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchManager.java
@@ -944,8 +944,8 @@
         @Override
         public void onMainFrameNavigation(String url, boolean isExternalUrl, boolean isFailure) {
             if (isExternalUrl) {
-                if (ContextualSearchFieldTrial.isAmpAsSeparateTabEnabled() && mPolicy.isAmpUrl(url)
-                        && mSearchPanel.didTouchContent()) {
+                if (!ContextualSearchFieldTrial.isAmpAsSeparateTabDisabled()
+                        && mPolicy.isAmpUrl(url) && mSearchPanel.didTouchContent()) {
                     onExternalNavigation(url);
                 }
             } else {