Add more SampleApp support to viewer.

Fixes loading a Sample as first slide.
Adds char input.
Adds --slide and --list options.

Change-Id: I34b66818e3673fcfdc649443e7d9dfb74b478062
Reviewed-on: https://skia-review.googlesource.com/8445
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
diff --git a/tools/viewer/SampleSlide.cpp b/tools/viewer/SampleSlide.cpp
index 5e02ff1..00ee534 100644
--- a/tools/viewer/SampleSlide.cpp
+++ b/tools/viewer/SampleSlide.cpp
@@ -36,6 +36,12 @@
     fView = nullptr;
 }
 
+bool SampleSlide::onChar(SkUnichar c) {
+    SkEvent evt(gCharEvtName);
+    evt.setFast32(c);
+    return fView->doQuery(&evt);
+}
+
 #if defined(SK_BUILD_FOR_ANDROID)
 // these are normally defined in SkOSWindow_unix, but we don't
 // want to include that