Set maximum output size for scaled-image-cache images

Accessable via:
  SkScaledImageCache::{G,S}etMaximumOutputSizeForHighQualityFilter

Also, a unit test.

BUG=389439
R=humper@google.com, tomhudson@google.com, reveman@chromium.org, vangelis@chromium.org, reed@google.com

Author: halcanary@google.com

Review URL: https://codereview.chromium.org/394003003
diff --git a/gyp/tests.gypi b/gyp/tests.gypi
index 99a52a4..6a64479 100644
--- a/gyp/tests.gypi
+++ b/gyp/tests.gypi
@@ -162,6 +162,7 @@
     '../tests/SHA1Test.cpp',
     '../tests/SListTest.cpp',
     '../tests/ScalarTest.cpp',
+    '../tests/ScaledImageCache.cpp',
     '../tests/SerializationTest.cpp',
     '../tests/ShaderImageFilterTest.cpp',
     '../tests/ShaderOpacityTest.cpp',