Move HWUI boilerplate into utils/android

Duplicate code from the HWUI backends for DM and nanobench
moves into a single place, saving a hundred lines or more of
cut-and-paste.

There's some indication that this increases the incidence of
SkCanvas "Unable to find device for layer." warnings, but no
clear degradation in test results.

R=djsollen@google.com,mtklein@google.com
BUG=skia:3589

Review URL: https://codereview.chromium.org/1036303002
diff --git a/gyp/utils.gyp b/gyp/utils.gyp
index db90301..73a9d32 100644
--- a/gyp/utils.gyp
+++ b/gyp/utils.gyp
@@ -139,6 +139,8 @@
       'sources': [
         '../src/utils/android/SkAndroidSDKCanvas.h',
         '../src/utils/android/SkAndroidSDKCanvas.cpp',
+        '../src/utils/android/SkHwuiRenderer.h',
+        '../src/utils/android/SkHwuiRenderer.cpp',
       ],
       'direct_dependent_settings': {
         'include_dirs': [