Move fontmgr_bounds label setting to checkbox.

The fontmgr_bounds gm has an option to show the name of the font and the
glyph ids of the glyphs with extreme bounds. This was previously done
with a command line flag label_fontmgr_bounds. However, this information
is generally only useful in the viewer application, so change this to a
control.

This also adds bool field handling in viewer.

Change-Id: Idbdbb08e9516ec49a96f9baa320acd6fe44e95ca
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/203175
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index 6cad26e..f222a37 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -1821,6 +1821,13 @@
                                 if (ImGui::SliderFloat(name, &val[0], val[1], val[2])) {
                                     controls.setScalars(name, 3, val);
                                 }
+                            } else if (type == SkMetaData::kBool_Type) {
+                                bool val;
+                                SkASSERT(count == 1);
+                                controls.findBool(name, &val);
+                                if (ImGui::Checkbox(name, &val)) {
+                                    controls.setBool(name, val);
+                                }
                             }
                         }
                         fSlides[fCurrentSlide]->onSetControls(controls);