Cleanup: Use SkAutoGraphics in gm and tests.

BUG=None
R=bsalomon@google.com

Review URL: https://codereview.chromium.org/704413002
diff --git a/tests/skia_test.cpp b/tests/skia_test.cpp
index 3d76c3a..1b5584b 100644
--- a/tests/skia_test.cpp
+++ b/tests/skia_test.cpp
@@ -127,7 +127,7 @@
     }
 #endif
 
-    SkGraphics::Init();
+    SkAutoGraphics ag;
 
     {
         SkString header("Skia UnitTests:");
@@ -213,7 +213,6 @@
         SkDebugf("\nFinished %d tests, %d failures, %d skipped. (%d internal tests)",
                  toRun, failCount, skipCount, reporter.countTests());
     }
-    SkGraphics::Term();
 
     SkDebugf("\n");
     return (failCount == 0) ? 0 : 1;