Use upper case hex in viewer's zoom window

Bug: skia:
Change-Id: I5452dd557e103ccf75fb70312d32ad7615a830ed
Reviewed-on: https://skia-review.googlesource.com/c/193468
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index 08d5cf5..8752a27 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -1885,7 +1885,7 @@
             SkImageInfo info = SkImageInfo::MakeN32Premul(1, 1);
             if (fLastImage->readPixels(info, &pixel, info.minRowBytes(), xInt, yInt)) {
                 ImGui::SameLine();
-                ImGui::Text("(X, Y): %d, %d RGBA: %x %x %x %x",
+                ImGui::Text("(X, Y): %d, %d RGBA: %X %X %X %X",
                             xInt, yInt,
                             SkGetPackedR32(pixel), SkGetPackedG32(pixel),
                             SkGetPackedB32(pixel), SkGetPackedA32(pixel));