Add Xlib support to viewer

tools/viewer/sk_app/unix/Window_unix.h

+/*
+* Copyright 2016 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+
+#ifndef Window_unix_DEFINED
+#define Window_unix_DEFINED
+
+#include <X11/Xlib.h>
+#include "../Window.h"
+#include "SkChecksum.h"
+#include "SkTDynamicHash.h"
+
+typedef Window XWindow;
+
+namespace sk_app {
+
+struct ContextPlatformData_unix {
+    Display* fDisplay;
+    XWindow  fHWnd;
+    VisualID fVisualID;
+};
+
+class Window_unix : public Window {
+public:
+    Window_unix() : Window() {}
+    ~Window_unix() override {}
+
+    bool init(Display* display);
+
+    void setTitle(const char*) override;
+    void show() override;
+
+    bool attach(BackendType attachType, const DisplayParams& params) override;
+
+    void onInval() override;
+
+    bool handleEvent(const XEvent& event);
+
+    static const XWindow& GetKey(const Window_unix& w) {
+        return w.fHWnd;
+    }
+
+    static uint32_t Hash(const XWindow& w) {
+        return SkChecksum::Mix(w);
+    }
+
+    static SkTDynamicHash<Window_unix, XWindow> gWindowMap;
+
+    void markPendingPaint() { fPendingPaint = true; }
+    void finishPaint() { 
+        if (fPendingPaint) {
+            this->onPaint(); 
+            fPendingPaint = false; 
+        }
+    }
+
+    void markPendingResize(int width, int height) { 
+        fPendingWidth = width; 
+        fPendingHeight = height;
+        fPendingResize = true;
+    }
+    void finishResize() { 
+        if (fPendingResize) {
+            this->onResize(fPendingWidth, fPendingHeight); 
+            fPendingResize = false;
+        } 
+    }
+
+private:
+    Display* fDisplay;
+    XWindow  fHWnd;
+
+    Atom     fWmDeleteMessage;
+
+    bool     fPendingPaint;
+    int      fPendingWidth;
+    int      fPendingHeight;
+    bool     fPendingResize;
+};
+
+}   // namespace sk_app
+
+#endif