Fix adb_gdb script.

build/android/adb_gdb

 #!/bin/bash
 #
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 
 # A generic script used to attach to a running Chromium process and
 # debug it. Most users should not use this directly, but one of the
 # wrapper scripts like adb_gdb_content_shell
@@ skipping 529 matching lines @@
   fi
   ANDROID_TOOLCHAIN=$TOOLCHAIN
 fi
 
 # Cosmetic: Remove trailing directory separator.
 ANDROID_TOOLCHAIN=${ANDROID_TOOLCHAIN%/}
 
 # Find host GDB client binary
 if [ -z "$GDB" ]; then
   GDB=$(which $ANDROID_TOOLCHAIN/*-$GDBEXEPOSTFIX 2>/dev/null | head -1)
-  if [ -z "$GDBSERVER" ]; then
+  if [ -z "$GDB" ]; then
     panic "Can't find Android gdb client in your path, check your \
 --toolchain or --gdb path."
   fi
   log "Host gdb client: $GDB"
 fi
 
 # Find gdbserver binary, we will later push it to /data/local/tmp
 # This ensures that both gdbserver and $GDB talk the same binary protocol,
 # otherwise weird problems will appear.
 #
@@ skipping 398 matching lines @@
 
 if [ "$VERBOSE" -gt 0 ]; then
   echo "### START $COMMANDS"
   cat $COMMANDS
   echo "### END $COMMANDS"
 fi
 
 log "Launching gdb client: $GDB $GDBARGS -x $COMMANDS"
 $GDB $GDBARGS -x $COMMANDS &&
 rm -f "$GDBSERVER_PIDFILE"