Making overview panel accessible via Tab

Keyboard navigation of AllAppsContainerView is broken in TOT; disabling
focusing there is necessary for Recents.

Bug: 72222505
Test: Manual
Change-Id: I85d544f7c8dbdaf12e49de51c6626bbc3dc32917

quickstep/res/layout/task.xml

@@ -13,9 +13,11 @@
      See the License for the specific language governing permissions and
      limitations under the License.
 -->
-<com.android.quickstep.views.TaskView xmlns:android="http://schemas.android.com/apk/res/android"
+<com.android.quickstep.views.TaskView
+    xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:focusable="false"
     android:elevation="4dp">
 
     <com.android.quickstep.views.TaskThumbnailView
@@ -29,5 +31,6 @@
         android:layout_width="@dimen/task_thumbnail_icon_size"
         android:layout_height="@dimen/task_thumbnail_icon_size"
         android:importantForAccessibility="no"
+        android:focusable="false"
         android:layout_gravity="top|center_horizontal" />
 </com.android.quickstep.views.TaskView>

quickstep/src/com/android/quickstep/views/ClearAllButton.java

@@ -19,6 +19,7 @@ package com.android.quickstep.views;
 import static android.view.accessibility.AccessibilityNodeInfo.ACTION_ACCESSIBILITY_FOCUS;
 
 import android.content.Context;
+import android.graphics.Rect;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.util.AttributeSet;
@@ -43,4 +44,12 @@ public class ClearAllButton extends Button {
         }
         return res;
     }
+
+    @Override
+    protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
+        super.onFocusChanged(focused, direction, previouslyFocusedRect);
+        if (focused) {
+            mRecentsView.revealClearAllButton();
+        }
+    }
 }

quickstep/src/com/android/quickstep/views/RecentsView.java

@@ -41,6 +41,7 @@ import android.graphics.drawable.Drawable;
 import android.os.Build;
 import android.os.Handler;
 import android.os.UserHandle;
+import android.support.annotation.Nullable;
 import android.text.Layout;
 import android.text.StaticLayout;
 import android.text.TextPaint;
@@ -967,6 +968,13 @@ public abstract class RecentsView<T extends BaseActivity> extends PagedView impl
         if (event.getAction() == KeyEvent.ACTION_DOWN) {
             switch (event.getKeyCode()) {
                 case KeyEvent.KEYCODE_TAB:
+                    if (!event.isAltPressed() &&
+                            getNextPage() ==
+                                    (event.isShiftPressed() ? 0 : getChildCount() - 1)) {
+                        // If not Alt-Tab navigation, don't loop forever in the carousel and leave
+                        // it once we reached the end.
+                        return false;
+                    }
                     snapToPageRelative(event.isShiftPressed() ? -1 : 1);
                     return true;
                 case KeyEvent.KEYCODE_DPAD_RIGHT:
@@ -992,6 +1000,22 @@ public abstract class RecentsView<T extends BaseActivity> extends PagedView impl
         return super.dispatchKeyEvent(event);
     }
 
+    @Override
+    protected void onFocusChanged(boolean gainFocus, int direction,
+            @Nullable Rect previouslyFocusedRect) {
+        super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
+        if (gainFocus && getChildCount() > 0) {
+            switch (direction) {
+                case FOCUS_FORWARD:
+                    setCurrentPage(0);
+                    break;
+                case FOCUS_BACKWARD:
+                    setCurrentPage(getChildCount() - 1);
+                    break;
+            }
+        }
+    }
+
     public void snapToTaskAfterNext() {
         snapToPageRelative(1);
     }
@@ -1303,6 +1327,7 @@ public abstract class RecentsView<T extends BaseActivity> extends PagedView impl
     }
 
     public void revealClearAllButton() {
+        setCurrentPage(getChildCount() - 1); // Loads tasks info if needed.
         scrollTo(mIsRtl ? 0 : computeMaxScrollX(), 0);
     }
 

quickstep/src/com/android/quickstep/views/RecentsViewContainer.java

@@ -25,10 +25,13 @@ import android.util.AttributeSet;
 import android.util.FloatProperty;
 import android.view.Gravity;
 import android.view.MotionEvent;
+import android.view.View;
 
 import com.android.launcher3.InsettableFrameLayout;
 import com.android.launcher3.R;
 
+import java.util.ArrayList;
+
 public class RecentsViewContainer extends InsettableFrameLayout {
     public static final FloatProperty<RecentsViewContainer> CONTENT_ALPHA =
             new FloatProperty<RecentsViewContainer>("contentAlpha") {
@@ -104,4 +107,11 @@ public class RecentsViewContainer extends InsettableFrameLayout {
         mRecentsView.setContentAlpha(alpha);
         setVisibility(alpha > 0 ? VISIBLE : GONE);
     }
+
+    @Override
+    public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
+        // Carousel is first in tab order.
+        views.add(mRecentsView);
+        views.add(mClearAllButton);
+    }
 }

res/layout/all_apps.xml

@@ -23,8 +23,7 @@
     android:layout_height="match_parent"
     android:clipChildren="true"
     android:clipToPadding="false"
-    android:focusable="true"
-    android:focusableInTouchMode="true"
+    android:focusable="false"
     android:saveEnabled="false" >
 
     <include layout="@layout/all_apps_rv_layout" />

src/com/android/launcher3/views/ScrimView.java

@@ -118,6 +118,7 @@ public class ScrimView extends View implements Insettable, OnChangeListener,
         ViewCompat.setAccessibilityDelegate(this, mAccessibilityHelper);
 
         mAM = (AccessibilityManager) context.getSystemService(ACCESSIBILITY_SERVICE);
+        setFocusable(false);
     }
 
     @NonNull