Linux Skia: add an option to build a canvas from a provided memory buffer

skia/ext/platform_canvas_linux.cc

 // Copyright (c) 2006-2008 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.
 
 #include "skia/ext/platform_canvas_linux.h"
 
 #include "skia/ext/platform_device_linux.h"
 #include "skia/ext/bitmap_platform_device_linux.h"
 #include "SkTypes.h"
 
+#include <cairo/cairo.h>
+
 namespace skia {
 
 PlatformCanvasLinux::PlatformCanvasLinux() : SkCanvas() {
 }
 
 PlatformCanvasLinux::PlatformCanvasLinux(int width, int height, bool is_opaque)
     : SkCanvas() {
   if (!initialize(width, height, is_opaque))
     SK_CRASH();
 }
@@ skipping 24 matching lines @@
   SkASSERT(config == SkBitmap::kARGB_8888_Config);
   return createPlatformDevice(width, height, is_opaque);
 }
 
 SkDevice* PlatformCanvasLinux::createPlatformDevice(int width,
                                                     int height,
                                                     bool is_opaque) {
   return BitmapPlatformDeviceLinux::Create(width, height, is_opaque);
 }
 
+// static
+size_t PlatformCanvasLinux::StrideForWidth(unsigned width) {
+  return cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, width);
+}
+
 }  // namespace skia