Clean up code for custom slide GUIs

Bailing out early caused controls to flicker on/off if one was being
interacted with. No need to rebuild the window (paramsChanged), the GUI
is up, so we're already repainting.

Change-Id: I0751271962075dff22b19f60f4d1dc81c9232f58
Reviewed-on: https://skia-review.googlesource.com/145335
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index f88dfbb..05a030c 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -1670,19 +1670,17 @@
                         const char* name;
                         SkMetaData::Type type;
                         int count;
-                        bool found = false;
-                        while ((name = iter.next(&type, &count)) != nullptr && found == false) {
+                        while ((name = iter.next(&type, &count)) != nullptr) {
                             if (type == SkMetaData::kScalar_Type) {
                                 float val[3];
                                 SkASSERT(count == 3);
                                 controls.findScalars(name, &count, val);
                                 if (ImGui::SliderFloat(name, &val[0], val[1], val[2])) {
                                     controls.setScalars(name, 3, val);
-                                    fSlides[fCurrentSlide]->onSetControls(controls);
-                                    found = paramsChanged = true;
                                 }
                             }
                         }
+                        fSlides[fCurrentSlide]->onSetControls(controls);
                     }
                 }
             }