Optionally clear PlatformCanvas instances.

skia/ext/platform_canvas.cc

Index: skia/ext/platform_canvas.cc
===================================================================
--- skia/ext/platform_canvas.cc	(revision 123041)
+++ skia/ext/platform_canvas.cc	(working copy)
@@ -31,12 +31,22 @@
 }
 
 SkCanvas* CreateBitmapCanvas(int width, int height, bool is_opaque) {
-  return new PlatformCanvas(width, height, is_opaque);
+  return CreateBitmapCanvas(width, height,
+                            PlatformDevice::GetDefaultFlags(is_opaque));
 }
 
+SkCanvas* CreateBitmapCanvas(int width, int height, int flags) {
+  return new PlatformCanvas(width, height, flags);
+}
+
 SkCanvas* TryCreateBitmapCanvas(int width, int height, bool is_opaque) {
+  return TryCreateBitmapCanvas(width, height,
+                               PlatformDevice::GetDefaultFlags(is_opaque));
+}
+
+SkCanvas* TryCreateBitmapCanvas(int width, int height, int flags) {
   PlatformCanvas* canvas = new PlatformCanvas();
-  if (!canvas->initialize(width, height, is_opaque)) {
+  if (!canvas->initialize(width, height, flags)) {
     delete canvas;
     canvas = NULL;
   }