Expand VisualBench to a real benching tool

include/views/SkOSWindow_Unix.h

Index: include/views/SkOSWindow_Unix.h
diff --git a/include/views/SkOSWindow_Unix.h b/include/views/SkOSWindow_Unix.h
index 78670cde133003bccd9654bce0c6cb263266c8ee..4b7ee93d601cbfa259066bf0d8aecb0569849bbb 100644
--- a/include/views/SkOSWindow_Unix.h
+++ b/include/views/SkOSWindow_Unix.h
@@ -48,6 +48,7 @@ public:
 
     void setFullscreen(bool) override;
     void setVsync(bool) override;
+    void closeWindow() override;
 
 protected:
     // Overridden from from SkWindow:
@@ -64,7 +65,9 @@ private:
     void doPaint();
     void mapWindowAndWait();
 
-    void closeWindow();
+    // Forcefully closes the window.  If a graceful shutdown is desired then call the public
+    // closeWindow method
+    void internalCloseWindow();
     void initWindow(int newMSAASampleCount, AttachmentInfo* info);
 
     SkUnixWindow fUnixWindow;