Transaction_test refactoring continued

Minor refactor

Bug: 140128949
Test: build, boot, SurfaceFlinger_test
Change-Id: Ibeed4b4feb102d8ee6cf57c2deabb53f41177f0a
diff --git a/services/surfaceflinger/tests/utils/ScreenshotUtils.h b/services/surfaceflinger/tests/utils/ScreenshotUtils.h
index 02e7623..5480b00 100644
--- a/services/surfaceflinger/tests/utils/ScreenshotUtils.h
+++ b/services/surfaceflinger/tests/utils/ScreenshotUtils.h
@@ -76,7 +76,7 @@
 
     void expectColor(const Rect& rect, const Color& color, uint8_t tolerance = 0) {
         ASSERT_EQ(HAL_PIXEL_FORMAT_RGBA_8888, mOutBuffer->getPixelFormat());
-        expectBufferColor(mOutBuffer, mPixels, rect, color, tolerance);
+        TransactionUtils::expectBufferColor(mOutBuffer, mPixels, rect, color, tolerance);
     }
 
     void expectBorder(const Rect& rect, const Color& color, uint8_t tolerance = 0) {