Fix permission check bypass in IMMS#dump()

This is a follow up CL to our previous CL [1], which enabled IME
tracing result to be automatically included into the bugreport.

In the previous CL, we checked android.Manifest.permission.DUMP in
IMMS#doDump() not in IMMS#dump(), which means there was a chance that
some priviledged operations could be triggered by a user-mode
application.  So far the only actual imprecation is that a user-mode
process can restart an on-going IME trace session, but in general such
an operation should be allowed only to processes that have
android.Manifest.permission.DUMP or shell access.

With this CL, all the operations inside IMMS#dump() will require
android.Manifest.permission.DUMP again as we did before the previous
CL was submitted.

Other than that, there should be no behavior change in this CL.

This is a preparation to fix another unintentional behavior change
(Bug 177462676), which was also accidentally introduced in the same
CL.

 [1]: Ie87eb8423e2bb70f28c330983d45b95e2e07062d
      ac24994aaa

Bug: 154348613
Bug: 167948910
Bug: 177462676
Test: Manually done as follows.
  1. adb shell ime tracing start
  2. adb logcat -s imeTracing:*
       Make sure IME tracing started.
  3. adb shell am start -a android.intent.action.DIAL
  4. adb bugreport bugreport.zip
  5. adb logcat -s imeTracing:*
       Make sure IME tracing is stopped then restarted.
  6. unzip -v bugreport.zip | grep ime_trace_clients.pb
       Make sure "ime_trace_clients.pb" is included.
Change-Id: I3de965bc2993df67b046f3e6c09ece11047d227e

services/core/java/com/android/server/inputmethod/InputMethodManagerService.java

@@ -5227,6 +5227,8 @@ public class InputMethodManagerService extends IInputMethodManager.Stub
 
     @Override
     protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
+        if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;
+
         boolean asProto = false;
         for (int argIndex = 0; argIndex < args.length; argIndex++) {
             if (args[argIndex].equals(PROTO_ARG)) {
@@ -5249,8 +5251,6 @@ public class InputMethodManagerService extends IInputMethodManager.Stub
     }
 
     private void doDump(FileDescriptor fd, PrintWriter pw, String[] args, boolean useProto) {
-        if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;
-
         if (useProto) {
             final ProtoOutputStream proto = new ProtoOutputStream(fd);
             dumpDebug(proto, InputMethodManagerServiceTraceProto.INPUT_METHOD_MANAGER_SERVICE);