Quickly fix the double to SkScalar issue

tools/viewer/Viewer.cpp

Index: tools/viewer/Viewer.cpp
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index 465a7aad4d31434f57b863c879c660c2e3fc912b..48d2c41112efc43c583aeda1ae00b00626765b4e 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -350,7 +350,7 @@ void Viewer::drawSlide(SkCanvas* canvas, bool inSplitScreen) {
         SkRect contentRect = fWindow->getContentRect();
         // If inSplitScreen, translate the image half screen to the right.
         // Thus we have two copies of the image on each half of the screen.
-        contentRect.fLeft += inSplitScreen ? (contentRect.fRight - contentRect.fLeft) * 0.5 : 0;
+        contentRect.fLeft += inSplitScreen ? (contentRect.fRight - contentRect.fLeft) * 0.5f : 0f;
         canvas->clipRect(contentRect);
         canvas->translate(contentRect.fLeft, contentRect.fTop);
     }