Hide tab switcher button instead of removing in HTS

Previously the tab switcher button was removed when HTS was enabled.
This is incorrect since accessibility mode could mean reverting to using
the old tab switcher top toolbar with the tab switcher button. This CL
hides and shows the tab switcher button depending on the accessibility
state.

Bug: 914858

Change-Id: I1b74f5ed2e94380e260d2a4c6f0fb746f270e2e5
Reviewed-on: https://chromium-review.googlesource.com/c/1385126
Commit-Queue: Pedro Amaral <amaralp@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619848}

chrome/android/java/src/org/chromium/chrome/browser/toolbar/top/TabSwitcherModeTTPhone.java

@@ -43,11 +43,11 @@ public class TabSwitcherModeTTPhone extends OptimizedFrameLayout
     private IncognitoStateProvider mIncognitoStateProvider;
 
     private @Nullable IncognitoToggleTabLayout mIncognitoToggleTabLayout;
-    private @Nullable ToggleTabStackButton mToggleTabStackButton;
 
-    // The following two buttons are not used when Duet is enabled.
+    // The following three buttons are not used when Duet is enabled.
     private @Nullable NewTabButton mNewTabButton;
     private @Nullable MenuButton mMenuButton;
+    private @Nullable ToggleTabStackButton mToggleTabStackButton;
 
     private int mPrimaryColor;
     private boolean mUseLightIcons;
@@ -74,7 +74,16 @@ public class TabSwitcherModeTTPhone extends OptimizedFrameLayout
 
         if (isBottomToolbarEnabled) {
             UiUtils.removeViewFromParent(mNewTabButton);
+            mNewTabButton.destroy();
+            mNewTabButton = null;
+
             UiUtils.removeViewFromParent(mMenuButton);
+            mMenuButton.destroy();
+            mMenuButton = null;
+
+            UiUtils.removeViewFromParent(mToggleTabStackButton);
+            mToggleTabStackButton.destroy();
+            mToggleTabStackButton = null;
         } else {
             // TODO(twellington): Try to make NewTabButton responsible for handling its own clicks.
             //                    TabSwitcherBottomToolbarCoordinator also uses NewTabButton and
@@ -86,9 +95,7 @@ public class TabSwitcherModeTTPhone extends OptimizedFrameLayout
 
         if (usingHorizontalTabSwitcher()
                 && PrefServiceBridge.getInstance().isIncognitoModeEnabled()) {
-            inflateIncognitoToggle();
-        } else if (isBottomToolbarEnabled) {
-            removeToggleTabStackButton();
+            updateTabSwitchingElements(true);
         }
     }
 
@@ -246,11 +253,9 @@ public class TabSwitcherModeTTPhone extends OptimizedFrameLayout
     void onAccessibilityStatusChanged(boolean enabled) {
         if (mNewTabButton != null) mNewTabButton.onAccessibilityStatusChanged();
 
-        if (mIncognitoToggleTabLayout != null) {
-            mIncognitoToggleTabLayout.setVisibility(enabled ? View.GONE : View.VISIBLE);
-        } else if (usingHorizontalTabSwitcher()
+        if (ChromeFeatureList.isEnabled(ChromeFeatureList.HORIZONTAL_TAB_SWITCHER_ANDROID)
                 && PrefServiceBridge.getInstance().isIncognitoModeEnabled()) {
-            inflateIncognitoToggle();
+            updateTabSwitchingElements(!enabled);
         }
 
         updatePrimaryColorAndTint();
@@ -316,15 +321,23 @@ public class TabSwitcherModeTTPhone extends OptimizedFrameLayout
         if (mTabModelSelector != null) {
             mIncognitoToggleTabLayout.setTabModelSelector(mTabModelSelector);
         }
+    }
 
-        removeToggleTabStackButton();
+    private void setIncognitoToggleVisibility(boolean showIncognitoToggle) {
+        if (mIncognitoToggleTabLayout == null) {
+            if (showIncognitoToggle) inflateIncognitoToggle();
+        } else {
+            mIncognitoToggleTabLayout.setVisibility(showIncognitoToggle ? View.VISIBLE : View.GONE);
+        }
     }
 
-    private void removeToggleTabStackButton() {
+    private void setToggleTabStackButtonVisibility(boolean showToggleTabStackButton) {
         if (mToggleTabStackButton == null) return;
+        mToggleTabStackButton.setVisibility(showToggleTabStackButton ? View.VISIBLE : View.GONE);
+    }
 
-        UiUtils.removeViewFromParent(mToggleTabStackButton);
-        mToggleTabStackButton.destroy();
-        mToggleTabStackButton = null;
+    private void updateTabSwitchingElements(boolean showIncognitoToggle) {
+        setIncognitoToggleVisibility(showIncognitoToggle);
+        setToggleTabStackButtonVisibility(!showIncognitoToggle);
     }
 }