Fix SampleApp compilation with skia_gpu=0

samplecode/SampleApp.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SampleApp.h"
 
 #include "OverView.h"
@@ skipping 354 matching lines @@
 
     GrContext* getGrContext() override {
 #if SK_SUPPORT_GPU
         return fCurContext;
 #else
         return nullptr;
 #endif
     }
 
     int numColorSamples() const override {
+#if SK_SUPPORT_GPU
         return fMSAASampleCount;
+#else
+        return 0;
+#endif
     }
 
     int getColorBits() override {
 #if SK_SUPPORT_GPU
         return fActualColorBits;
 #else
         return 24;
 #endif
     }
 
@@ skipping 1918 matching lines @@
 #ifdef SK_BUILD_FOR_MAC
     setenv("ANDROID_ROOT", "/android/device/data", 0);
 #endif
     SkGraphics::Init();
     SkEvent::Init();
 }
 
 void application_term() {
     SkEvent::Term();
 }