update devicelooper to skip internal tiles that are empty, and unittests

BUG=

Review URL: https://codereview.chromium.org/23463040

git-svn-id: http://skia.googlecode.com/svn/trunk/gyp@11331 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests.gyp b/tests.gyp
index aacffc9..227f644 100644
--- a/tests.gyp
+++ b/tests.gyp
@@ -46,6 +46,7 @@
         '../tests/DataRefTest.cpp',
         '../tests/DeferredCanvasTest.cpp',
         '../tests/DequeTest.cpp',
+        '../tests/DeviceLooperTest.cpp',
         '../tests/DrawBitmapRectTest.cpp',
         '../tests/DrawPathTest.cpp',
         '../tests/DrawTextTest.cpp',