Add debug for ANR

Help for bug 17721767.

Change-Id: If863f3e6536be8af2c189dcc37d503c4d6b663b4
diff --git a/services/core/java/com/android/server/wm/DisplayContent.java b/services/core/java/com/android/server/wm/DisplayContent.java
index b0feca8..f57adaf 100644
--- a/services/core/java/com/android/server/wm/DisplayContent.java
+++ b/services/core/java/com/android/server/wm/DisplayContent.java
@@ -379,14 +379,18 @@
         pw.println("  Application tokens in top down Z order:");
         int ndx = 0;
         for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
-            ArrayList<Task> tasks = mStacks.get(stackNdx).getTasks();
+            final TaskStack stack = mStacks.get(stackNdx);
+            pw.print("  mStackId="); pw.println(stack.mStackId);
+            ArrayList<Task> tasks = stack.getTasks();
             for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
-                AppTokenList tokens = tasks.get(taskNdx).mAppTokens;
-                for (int tokenNdx = tokens.size() - 1; tokenNdx >= 0; --tokenNdx) {
+                final Task task = tasks.get(taskNdx);
+                pw.print("    mTaskId="); pw.println(task.taskId);
+                AppTokenList tokens = task.mAppTokens;
+                for (int tokenNdx = tokens.size() - 1; tokenNdx >= 0; --tokenNdx, ++ndx) {
                     final AppWindowToken wtoken = tokens.get(tokenNdx);
-                    pw.print("  App #"); pw.print(ndx++);
+                    pw.print("    Activity #"); pw.print(tokenNdx);
                             pw.print(' '); pw.print(wtoken); pw.println(":");
-                    wtoken.dump(pw, "    ");
+                    wtoken.dump(pw, "      ");
                 }
             }
         }