Improve Ganesh helpers.

mojo/skia/ganesh_image_factory.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_SKIA_GANESH_IMAGE_FACTORY_H_
+#define MOJO_SKIA_GANESH_IMAGE_FACTORY_H_
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2extmojo.h>
+
+#include "base/callback.h"
+#include "mojo/skia/ganesh_context.h"
+#include "skia/ext/refptr.h"
+#include "third_party/skia/include/core/SkImageGenerator.h"
+
+class SkImage;
+
+namespace mojo {
+namespace skia {
+
+// Creates an SkImage from a GL texture.
+// The underlying texture must be kept alive for as long as the SkImage exists.
+// Invokes |release_callback| when the SkImage is deleted.
+::skia::RefPtr<SkImage> CreateImageFromTexture(
+    const GaneshContext::Scope& scope,
+    uint32_t texture_id,
+    uint32_t width,
+    uint32_t height,
+    const base::Closure& release_callback);
+
+// Generates backing content for SkImages from a texture mailbox.
+// If |sync_point| is non-zero, inserts a sync point into the command stream
+// before the image is first drawn.
+// It is the responsibility of the client of this class to ensure that
+// the mailbox name is valid at the time when the image is being drawn.
+class MailboxTextureImageGenerator : public SkImageGenerator {
+ public:
+  MailboxTextureImageGenerator(
+      const GLbyte mailbox_name[GL_MAILBOX_SIZE_CHROMIUM],
+      GLuint sync_point,
+      uint32_t width,
+      uint32_t height);
+  ~MailboxTextureImageGenerator() override;
+
+  GrTexture* onGenerateTexture(GrContext* context,
+                               const SkIRect* subset) override;
+
+ private:
+  GLbyte mailbox_name_[GL_MAILBOX_SIZE_CHROMIUM];
+  GLuint sync_point_;
+};
+
+}  // namespace skia
+}  // namespace mojo
+
+#endif  // MOJO_SKIA_GANESH_IMAGE_FACTORY_H_