Ensures action mode toolbar is hidden on tab change

This CL fixes a bug that removes tab strip upon
opening a new tab while text selection is made on tablets.
Made sure the action mode toolbar gets animated out
(if present) before new tab gets opened.

Bug: 807712
Change-Id: Icba04263d836733595696f12063c3b47afd314f0
Reviewed-on: https://chromium-review.googlesource.com/952602
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541615}

chrome/android/java/src/org/chromium/chrome/browser/toolbar/ActionModeController.java

@@ -174,6 +174,7 @@ public class ActionModeController {
      * Hide animation for the textview if the action bar is not visible.
      */
     public void startHideAnimation() {
+        if (!mShowingActionMode) return;
         if (mCurrentAnimation != null) mCurrentAnimation.cancel();
 
         mCurrentAnimation = ObjectAnimator.ofInt(mActionBarDelegate, TOP_MARGIN_ANIM_PROPERTY,

chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarManager.java

@@ -1246,6 +1246,12 @@ public class ToolbarManager implements ToolbarTabController, UrlFocusChangeListe
         mToolbarModel.setTab(tab, isIncognito);
 
         updateCurrentTabDisplayStatus();
+
+        // This method is called prior to action mode destroy callback for incognito <-> normal
+        // tab switch. Makes sure the action mode toolbar is hidden before selecting the new tab.
+        if (previousTab != null && wasIncognito != isIncognito && DeviceFormFactor.isTablet()) {
+            mActionModeController.startHideAnimation();
+        }
         if (previousTab != tab || wasIncognito != isIncognito) {
             if (previousTab != tab) {
                 if (previousTab != null) {