ui: Add RGBX_8888 buffer format.

ui/gl/gl_image_memory.h

Index: ui/gl/gl_image_memory.h
diff --git a/ui/gl/gl_image_memory.h b/ui/gl/gl_image_memory.h
index 4f1fe045920bdb68769b4b31057237e6c9f0cf7b..3ee67b29f99d909eedad34da52bfd5a2d027c596 100644
--- a/ui/gl/gl_image_memory.h
+++ b/ui/gl/gl_image_memory.h
@@ -16,10 +16,6 @@ class GL_EXPORT GLImageMemory : public GLImage {
  public:
   GLImageMemory(const Size& size, unsigned internalformat);
 
-  static bool StrideInBytes(size_t width,
-                            BufferFormat format,
-                            size_t* stride_in_bytes);
-
   bool Initialize(const unsigned char* memory, BufferFormat format);
 
   // Overridden from GLImage:
@@ -38,6 +34,8 @@ class GL_EXPORT GLImageMemory : public GLImage {
                             const Rect& bounds_rect,
                             const RectF& crop_rect) override;
 
+  static unsigned GetInternalFormatForTesting(BufferFormat format);
+
  protected:
   ~GLImageMemory() override;