Add android_ninja, like android_make for ninja.

platform_tools/android/bin/android_ninja

Index: platform_tools/android/bin/android_ninja
diff --git a/platform_tools/android/bin/android_ninja b/platform_tools/android/bin/android_ninja
new file mode 100755
index 0000000000000000000000000000000000000000..1af7ae1ac865ce500ceb477554936a83db0e60c1
--- /dev/null
+++ b/platform_tools/android/bin/android_ninja
@@ -0,0 +1,14 @@
+#!/bin/bash
+set -e
+
+rm -f .android_config   # If no -d flag is given, force the default device (not the last one).
+source android_setup.sh
+echo $DEVICE_ID > .android_config

[djsollen, 2013/09/27 14:07:50]

seems like we could refactor android_make so that we could share not only this
logic, but the ccache logic as well. 

[mtklein, 2013/09/30 15:41:58]

Yup.  As we talked about before, all that ccache logic was dead code.  I've
refactored android_make to share as much logic as possible.  android_ninja is
just a symlink to android_make now.

+
+exportVar GYP_GENERATORS ninja
+./gyp_skia
+
+OUT=$SKIA_OUT/${BUILDTYPE-Debug}

[djsollen, 2013/09/27 14:07:50]

The default string value is something I didn't know you could do, but it's just
what we need.  Can you just put a small comment there for us non-bash experts
that buildtype defaults to debug if not defined.

[mtklein, 2013/09/30 15:41:58]

Yeah, it's handy.  Done.

+ninja -C $OUT $APP_ARGS
+cd $OUT; ln -sf lib lib.target; cd - # android_run_skia looks in lib.target.
+