Make PluginInstance::PrintPDFOutput-metafile implementation agnostic on Linux.

printing/native_metafile_skia_wrapper.cc

+// Copyright (c) 2011 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 "base/logging.h"
+#include "printing/native_metafile_skia_wrapper.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkDevice.h"
+#include "third_party/skia/include/core/SkRefDict.h"
+
+namespace printing {
+
+namespace {
+
+SkRefDict& getRefDict(SkCanvas* canvas) {
+  DCHECK(canvas != NULL);
+
+  SkDevice* device = canvas->getDevice();
+  DCHECK(device != NULL);
+  return device->getRefDict();
+}
+
+}  // namespace
+
+// static
+const char* NativeMetafileSkiaWrapper::kNativeMetafileKey = "CrNativeMetafile";
+
+// static
+void NativeMetafileSkiaWrapper::SetMetafileOnCanvas(SkCanvas* canvas,
+                                                    NativeMetafile* metafile) {
+  NativeMetafileSkiaWrapper* wrapper = NULL;
+  if (metafile)

[Lei Zhang, 2011/03/24 21:28:27]

What happens if |metafile| is NULL? Do we need this check?

[vandebo (ex-Chrome), 2011/03/24 21:44:45]

There's no reason to store an entry in the SkRefDict if the value is NULL
(that's the value that will get returned anyway).  And setting a key to NULL in
the SkRefDict deletes any existing entry.  I only caught this myself on a second
read through of the change.

+    wrapper = new NativeMetafileSkiaWrapper(metafile);
+
+  SkRefDict& dict = getRefDict(canvas);
+  dict.set(kNativeMetafileKey, wrapper);
+  wrapper->unref();
+}
+
+// static
+NativeMetafile* NativeMetafileSkiaWrapper::GetMetafileFromCanvas(
+    SkCanvas* canvas) {
+  SkRefDict& dict = getRefDict(canvas);
+  SkRefCnt* value = dict.find(kNativeMetafileKey);
+  if (!value)
+    return NULL;
+
+  return static_cast<NativeMetafileSkiaWrapper*>(value)->metafile_;
+}
+
+NativeMetafileSkiaWrapper::NativeMetafileSkiaWrapper(NativeMetafile* metafile)
+    : metafile_(metafile) {
+}
+
+}  // namespace printing