Mark overridden destructors with 'override' and remove 'virtual'

This silences a new warning in clang 5.0

Change-Id: Ieb5b75a6ffed60107c3fd16075d2ecfd515b55e8
Reviewed-on: https://skia-review.googlesource.com/10006
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
diff --git a/samplecode/GMSampleView.h b/samplecode/GMSampleView.h
index 4d29190..6424b43 100644
--- a/samplecode/GMSampleView.h
+++ b/samplecode/GMSampleView.h
@@ -18,7 +18,7 @@
 
 public:
     GMSampleView(GM*);
-    virtual ~GMSampleView();
+    ~GMSampleView() override;
 
     static SkEvent* NewShowSizeEvt(bool doShowSize);
 
diff --git a/samplecode/OverView.cpp b/samplecode/OverView.cpp
index 0cd129e..62e8c2a 100644
--- a/samplecode/OverView.cpp
+++ b/samplecode/OverView.cpp
@@ -45,7 +45,7 @@
 class OverView : public SkView {
 public:
     OverView(int count, const SkViewFactory* factories[]);
-    virtual ~OverView();
+    ~OverView() override;
 
 protected:
     bool onEvent(const SkEvent&) override;
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index 79023a0..6b9a888 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -205,7 +205,7 @@
         fBackend = kNone_BackEndType;
     }
 
-    virtual ~DefaultDeviceManager() {
+    ~DefaultDeviceManager() override {
 #if SK_SUPPORT_GPU
         SkSafeUnref(fCurContext);
         SkSafeUnref(fCurIntf);
diff --git a/samplecode/SampleApp.h b/samplecode/SampleApp.h
index 7b0dbf4..e4c1f38 100644
--- a/samplecode/SampleApp.h
+++ b/samplecode/SampleApp.h
@@ -114,7 +114,7 @@
     };
 
     SampleWindow(void* hwnd, int argc, char** argv, DeviceManager*);
-    virtual ~SampleWindow();
+    ~SampleWindow() override;
 
     sk_sp<SkSurface> makeSurface() override {
         sk_sp<SkSurface> surface;
diff --git a/samplecode/SamplePathText.cpp b/samplecode/SamplePathText.cpp
index 26ffb9a..bb2142e 100644
--- a/samplecode/SamplePathText.cpp
+++ b/samplecode/SamplePathText.cpp
@@ -116,7 +116,7 @@
         , fBackMatrices(kNumPaths) {
     }
 
-    ~MovingPathText() {
+    ~MovingPathText() override {
         fBackgroundAnimationTask.wait();
     }
 
@@ -227,7 +227,7 @@
         : fFrontPaths(kNumPaths)
         , fBackPaths(kNumPaths) {}
 
-    ~WavyPathText() {
+    ~WavyPathText() override {
         fBackgroundAnimationTask.wait();
     }
 
diff --git a/samplecode/SampleSVGFile.cpp b/samplecode/SampleSVGFile.cpp
index efffb20..0be7944 100644
--- a/samplecode/SampleSVGFile.cpp
+++ b/samplecode/SampleSVGFile.cpp
@@ -20,7 +20,7 @@
 public:
     SVGFileView(const SkString& path)
         : fPath(path), fLabel(SkStringPrintf("[%s]", SkOSPath::Basename(path.c_str()).c_str())) {}
-    virtual ~SVGFileView() = default;
+    ~SVGFileView() override = default;
 
 protected:
     void onOnceBeforeDraw() override {