Revert "Use checked in android_tools Android NDK."

build/android/envsetup_functions.sh

Index: build/android/envsetup_functions.sh
diff --git a/build/android/envsetup_functions.sh b/build/android/envsetup_functions.sh
index 128d78fcf3078a20508e539d1983fe0bbe1b993b..0c7a2a0db821a96d1f55b0400e60e5cb4d1e25c7 100755
--- a/build/android/envsetup_functions.sh
+++ b/build/android/envsetup_functions.sh
@@ -146,10 +146,11 @@ common_gyp_vars() {
 #  > make
 ################################################################################
 sdk_build_init() {
-  # If ANDROID_NDK_ROOT is set when envsetup is run, use the ndk pointed to by
-  # the environment variable.  Otherwise, use the default ndk from the tree.
   if [ ! -d "${ANDROID_NDK_ROOT}" ]; then
-    export ANDROID_NDK_ROOT="${CHROME_SRC}/third_party/android_tools/ndk/"
+    echo "ANDROID_NDK_ROOT must be set to the path of Android NDK." >& 2
+    echo "which could be installed by" >& 2
+    echo "<chromium_tree>/src/build/install-build-deps-android-sdk.sh" >& 2
+    return 1
   fi
 
   # If ANDROID_SDK_ROOT is set when envsetup is run, use the sdk pointed to by