SF: tidy comments for luma sampling.

Tidying of const, comment and one internal fn name for
Region Luma sampling.

Test: libgui_test --gtest_filter="RegionSamp*"

Change-Id: I46895c8ed5b2e2045d7ce7444085585b62b5ab6e
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index df558e5..a59d45a 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -5485,13 +5485,13 @@
                                              static_cast<android_pixel_format>(reqPixelFormat), 1,
                                              usage, "screenshot");
 
-    return captureScreenCore(renderArea, traverseLayers, *outBuffer, useIdentityTransform);
+    return captureScreenCommon(renderArea, traverseLayers, *outBuffer, useIdentityTransform);
 }
 
-status_t SurfaceFlinger::captureScreenCore(RenderArea& renderArea,
-                                           TraverseLayersFunction traverseLayers,
-                                           const sp<GraphicBuffer>& buffer,
-                                           bool useIdentityTransform) {
+status_t SurfaceFlinger::captureScreenCommon(RenderArea& renderArea,
+                                             TraverseLayersFunction traverseLayers,
+                                             const sp<GraphicBuffer>& buffer,
+                                             bool useIdentityTransform) {
     // This mutex protects syncFd and captureResult for communication of the return values from the
     // main thread back to this Binder thread
     std::mutex captureMutex;