default to device type of last build if no device type is given

platform_tools/android/bin/android_setup.sh

 #!/bin/bash
 #
 # android_setup.sh: Sets environment variables used by other Android scripts.
 
 # Parse the arguments for a DEVICE_ID.
 DEVICE_ID=""
 DEVICE_SERIAL=""
 while (( "$#" )); do
   if [[ $(echo "$1" | grep "^-d$") != "" ]];
   then
@@ skipping 142 matching lines @@
 setup_device() {
   DEFINES="OS=android"
   DEFINES="${DEFINES} host_os=$(uname -s | sed -e 's/Linux/linux/;s/Darwin/mac/')"
   DEFINES="${DEFINES} skia_os=android"
   DEFINES="${DEFINES} android_base=${SCRIPT_DIR}/.."
   DEFINES="${DEFINES} skia_shared_lib=1"
 
   # Setup the build variation depending on the target device
   TARGET_DEVICE="$1"
 
+
   if [ -z "$TARGET_DEVICE" ]; then
-    echo "INFO: no target device type was specified so using the default 'arm_v7'"
-    TARGET_DEVICE="arm_v7"
+    if [ -f .android_config ]; then
+      TARGET_DEVICE=$(cat .android_config)
+      echo "INFO: no target device was specified so using the device (${TARGET_DEVICE}) from the most recent build"
+    else
+      TARGET_DEVICE="arm_v7"  
+      echo "INFO: no target device type was specified so using the default '${TARGET_DEVICE}'"
+    fi
   fi
 
   case $TARGET_DEVICE in
     nexus_s)
       DEFINES="${DEFINES} skia_arch_type=arm arm_neon=1 arm_version=7 arm_thumb=1"
       DEFINES="${DEFINES} skia_texture_cache_mb_limit=24"
       ANDROID_ARCH="arm"
       ;;
     nexus_4 | nexus_7 | nexus_10)
       DEFINES="${DEFINES} skia_arch_type=arm arm_neon=1 arm_version=7 arm_thumb=1"
@@ skipping 130 matching lines @@
   else
     $ADB $DEVICE_SERIAL push $HOST_SRC $ANDROID_DST
   fi
 }
 
 # Set up the device.
 setup_device "${DEVICE_ID}"
 if [[ "$?" != "0" ]]; then
   exit 1
 fi