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"
+
+namespace sk_app {
+
+struct ContextPlatformData_unix {
+    Display* fDisplay;
+    ::Window fHWnd;

[djsollen, 2016/05/23 18:13:06]

so X11 calls their class Window as well? can you do a typedef of ::Window to
something like XWindow?

[jvanverth1, 2016/05/23 18:19:10]

Done.

+    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 inval() override;
+
+    bool handleEvent(const XEvent& event);
+
+    static const ::Window& GetKey(const Window_unix& w) {
+        return w.fHWnd;
+    }
+
+    static uint32_t Hash(const ::Window& w) {
+        return SkChecksum::Mix(w);
+    }
+
+    static SkTDynamicHash<Window_unix,::Window> gWindowMap;
+
+private:
+    Display* fDisplay;
+    ::Window fHWnd;
+
+    Atom     fWmDeleteMessage;
+    double   fResizeTimer;
+    int      fExposeCount;
+};
+
+}   // namespace sk_app
+
+#endif