Start writing the GTK code for test_shell.

base/gfx/bitmap_platform_device_linux.h

Index: base/gfx/bitmap_platform_device_linux.h
diff --git a/base/gfx/bitmap_platform_device_linux.h b/base/gfx/bitmap_platform_device_linux.h
index 3059c2c30701f6ceeea4450118bf26d1b4dd5c02..96a640c1eed397089027d3ec446b3866054a4834 100644
--- a/base/gfx/bitmap_platform_device_linux.h
+++ b/base/gfx/bitmap_platform_device_linux.h
@@ -8,10 +8,22 @@
 #include "base/gfx/platform_device_linux.h"
 #include "base/ref_counted.h"
 
+#include "gdk-pixbuf/gdk-pixbuf.h"
+
 namespace gfx {
 
-// I'm trying to get away with defining as little as possible on this. Right
-// now, we don't do anything.
+// -----------------------------------------------------------------------------
+// This is the Linux bitmap backing for Skia. It's a GdkPixbuf of the correct
+// size and we implement a SkPixelRef in order that Skia can write directly to
+// the pixel memory backing the Pixbuf.
+//
+// We then provide an accessor for getting the pixbuf object and that can be
+// drawn to a GDK drawing area to display the rendering result.
+//
+// This is all quite ok for test_shell. In the future we will want to use
+// shared memory between the renderer and the main process at least. In this
+// case we'll probably create the pixbuf from a precreated region of memory.
+// -----------------------------------------------------------------------------
 class BitmapPlatformDeviceLinux : public PlatformDeviceLinux {
  public:
   /// Static constructor. I don't understand this, it's just a copy of the mac
@@ -22,7 +34,7 @@ class BitmapPlatformDeviceLinux : public PlatformDeviceLinux {
   /// you should probably be using Create(). This may become private later if
   /// we ever have to share state between some native drawing UI and Skia, like
   /// the Windows and Mac versions of this class do.
-  BitmapPlatformDeviceLinux(const SkBitmap& other);
+  BitmapPlatformDeviceLinux(const SkBitmap& other, GdkPixbuf* pixbuf);
   virtual ~BitmapPlatformDeviceLinux();
 
   // A stub copy constructor.  Needs to be properly implemented.
@@ -30,6 +42,11 @@ class BitmapPlatformDeviceLinux : public PlatformDeviceLinux {
 
   // Bitmaps aren't vector graphics.
   virtual bool IsVectorial() { return false; }
+
+  GdkPixbuf* pixbuf() const { return pixbuf_; }
+
+ private:
+  GdkPixbuf* pixbuf_;
 };
 
 }  // namespace gfx