Re-land unit test for clear bug (w/ AMD work-arounds)

Bug: 768134
Change-Id: I76e5e3ff5719b0d2f9c74d49dfa9e187e4da7c1f
Reviewed-on: https://skia-review.googlesource.com/60562
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-on: https://skia-review.googlesource.com/61221
diff --git a/tests/ClearTest.cpp b/tests/ClearTest.cpp
index c1c39dc..fca0318 100644
--- a/tests/ClearTest.cpp
+++ b/tests/ClearTest.cpp
@@ -11,6 +11,9 @@
 #include "GrContext.h"
 #include "GrRenderTargetContext.h"
 
+#include "SkCanvas.h"
+#include "SkSurface.h"
+
 static bool check_rect(GrRenderTargetContext* rtc, const SkIRect& rect, uint32_t expectedValue,
                        uint32_t* actualValue, int* failX, int* failY) {
     int w = rect.width();
@@ -212,8 +215,6 @@
     }
 }
 
-#if 0
-
 void fullscreen_clear_with_layer_test(skiatest::Reporter* reporter, GrContext* context) {
     const SkImageInfo ii = SkImageInfo::Make(400, 77, kRGBA_8888_SkColorType, kPremul_SkAlphaType);
 
@@ -280,5 +281,3 @@
 }
 
 #endif
-
-#endif