Remove minLayer and maxLayer from screenshot code.

When taking a full display screenshot, there's no longer a need for min
and max layer. Instead, the entire display will be screenshotted. If
only some layers should be screenshotted, then use the captureLayers method
instead. This was already the case for real code, but required some
clean up in Transaction_test

Test: Transaction_test
Change-Id: I774357b284ca9e026097f79fb7146e4931fa629a
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 341734c..f367275 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -121,10 +121,9 @@
                                                  useIdentityTransform, forSystem, outSyncFd);
     }
 
-    auto traverseLayersInDisplay(const sp<const DisplayDevice>& display, int32_t minLayerZ,
-                                 int32_t maxLayerZ, const LayerVector::Visitor& visitor) {
-        return mFlinger->SurfaceFlinger::traverseLayersInDisplay(display, minLayerZ, maxLayerZ,
-                                                                 visitor);
+    auto traverseLayersInDisplay(const sp<const DisplayDevice>& display,
+                                 const LayerVector::Visitor& visitor) {
+        return mFlinger->SurfaceFlinger::traverseLayersInDisplay(display, visitor);
     }
 
     /* ------------------------------------------------------------------------