Fixes for touch exclusion region

- Evaluate touch exclusion region on per-task basis, instead of per
  window. Smallest unit for exclusion is Task, if task has more than
  one app window, we still need to use the visible area of the task
  to do focus transfer properly.

- Only add back the touch region for focused task after all tasks
  are processed for eclusion, otherwise the focused area could be
  removed from exclusion incorrectly.

- Skip app windows that's exiting or hidden.

bug: 25494928

Change-Id: I972ba2149431557e7420b1095d9496a6cd821bdb
diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index 1b86488..46cd7cd 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -284,7 +284,12 @@
     boolean getMaxVisibleBounds(Rect out) {
         boolean foundTop = false;
         for (int i = mAppTokens.size() - 1; i >= 0; i--) {
-            final WindowState win = mAppTokens.get(i).findMainWindow();
+            final AppWindowToken token = mAppTokens.get(i);
+            // skip hidden (or about to hide) apps
+            if (token.mIsExiting || token.clientHidden || token.hiddenRequested) {
+                continue;
+            }
+            final WindowState win = token.findMainWindow();
             if (win == null) {
                 continue;
             }
@@ -413,14 +418,20 @@
         return mStack != null && mStack.mStackId == DOCKED_STACK_ID;
     }
 
-    WindowState getTopAppMainWindow() {
-        final int tokensCount = mAppTokens.size();
-        return tokensCount > 0 ? mAppTokens.get(tokensCount - 1).findMainWindow() : null;
+    WindowState getTopVisibleAppMainWindow() {
+        final AppWindowToken token = getTopVisibleAppToken();
+        return token != null ? token.findMainWindow() : null;
     }
 
-    AppWindowToken getTopAppWindowToken() {
-        final int tokensCount = mAppTokens.size();
-        return tokensCount > 0 ? mAppTokens.get(tokensCount - 1) : null;
+    AppWindowToken getTopVisibleAppToken() {
+        for (int i = mAppTokens.size() - 1; i >= 0; i--) {
+            final AppWindowToken token = mAppTokens.get(i);
+            // skip hidden (or about to hide) apps
+            if (!token.mIsExiting && !token.clientHidden && !token.hiddenRequested) {
+                return token;
+            }
+        }
+        return null;
     }
 
     @Override