Quickly fix the double to SkScalar issue

tools/viewer/Viewer.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "Viewer.h"
 
 #include "GMSlide.h"
@@ skipping 332 matching lines @@
 
 void Viewer::drawSlide(SkCanvas* canvas, bool inSplitScreen) {
     SkASSERT(!inSplitScreen || fWindow->supportsContentRect());
 
     int count = canvas->save();
 
     if (fWindow->supportsContentRect()) {
         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);
     }
 
     canvas->clear(SK_ColorWHITE);
     canvas->concat(fDefaultMatrix);
     canvas->concat(computeMatrix());
 
     canvas->getMetaData().setBool(kImageColorXformMetaData, inSplitScreen);
     fSlides[fCurrentSlide]->draw(canvas);
@@ skipping 194 matching lines @@
         bool newSplitScreen = stateValue.equals(kON);
         if (newSplitScreen != fSplitScreen) {
             fSplitScreen = newSplitScreen;
             fWindow->inval();
             updateUIState();
         }
     } else {
         SkDebugf("Unknown stateName: %s", stateName.c_str());
     }
 }