Check for third_party deps before compiling on android

platform_tools/android/bin/android_setup.sh

 function exportVar {
   NAME=$1
   VALUE=$2
   echo export $NAME=\"$VALUE\"
   export $NAME="$VALUE"
 }
 
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 # A valid Android SDK installation is required to build the sample app.
 if [ -z "$ANDROID_SDK_ROOT" ]; then
   ANDROID_TOOL=$(which android 2>/dev/null)
   if [ -z "$ANDROID_TOOL" ]; then
     echo "ERROR: Please define ANDROID_SDK_ROOT in your environment to point"
     echo "       to a valid Android SDK installation."
     return 1
   fi
   ANDROID_SDK_ROOT=$(cd $(dirname "$ANDROID_TOOL")/.. && pwd)
   exportVar ANDROID_SDK_ROOT "$ANDROID_SDK_ROOT"
 fi
 
 # ant is required to be installed on your system and in your PATH
 ant -version &> /dev/null
 if [[ "$?" != "0" ]]; then
   echo "ERROR: Unable to find ant. Please install it before proceeding."
   exit 1
 fi
 
+# check to see that gclient sync ran successfully
+THIRD_PARTY_EXTERNAL_DIR=${SCRIPT_DIR}/../third_party/externals
+if [ ! -d "$ANDROID_TOOLCHAIN" ]; then
+        echo ""
+        echo "ERROR: Unable to find the required third_party dependencies needed to build."
+        echo "       To fix this add the following line to your .gclient file and run 'gclient sync'"
+        echo "        target_os = ['android']"
+        echo ""
+        exit 1;
+fi
+
 # determine the toolchain that we will be using
 API_LEVEL=14
 
 if [[ -z "$NDK_REV" ]];
 then
     NDK_REV="8d"
 fi
 
 if [[ -z "$ANDROID_ARCH" ]];
 then
@@ skipping 141 matching lines @@
 # Use the "android" flavor of the Makefile generator for both Linux and OS X.
 exportVar GYP_GENERATORS "make-android"
 
 # Helper function so that when we run "make" to build for clank it exports
 # the toolchain variables to make.
 #make_android() {
 #  CC="$CROSS_CC" CXX="$CROSS_CXX" LINK="$CROSS_LINK" \
 #  AR="$CROSS_AR" RANLIB="$CROSS_RANLIB" \
 #    command make $*
 #}