refactor: move gfx::ImageSkia functions to their own util file (#19460)

* initial refactor

* fix lint

* 🚚🚚🚚🚚🚚

* change year in copyright?

* lint more

* remove bad code

* add missing header

* fix: add missing ifdef guard

* fix variable call

shell/common/skia_util.h

@@ -0,0 +1,44 @@
+// Copyright (c) 2019 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef SHELL_COMMON_SKIA_UTIL_H_
+#define SHELL_COMMON_SKIA_UTIL_H_
+
+#include <string>
+
+#include "ui/gfx/image/image_skia.h"
+
+namespace electron {
+
+namespace util {
+
+bool PopulateImageSkiaRepsFromPath(gfx::ImageSkia* image,
+                                   const base::FilePath& path);
+
+bool AddImageSkiaRepFromBuffer(gfx::ImageSkia* image,
+                               const unsigned char* data,
+                               size_t size,
+                               int width,
+                               int height,
+                               double scale_factor);
+
+bool AddImageSkiaRepFromJPEG(gfx::ImageSkia* image,
+                             const unsigned char* data,
+                             size_t size,
+                             double scale_factor);
+
+bool AddImageSkiaRepFromPNG(gfx::ImageSkia* image,
+                            const unsigned char* data,
+                            size_t size,
+                            double scale_factor);
+
+#if defined(OS_WIN)
+bool ReadImageSkiaFromICO(gfx::ImageSkia* image, HICON icon);
+#endif
+
+}  // namespace util
+
+}  // namespace electron
+
+#endif  // SHELL_COMMON_SKIA_UTIL_H_