Add skia extension to allow setting default fontmgr on linux. Use it to allow the linux blimp clien…

skia/ext/fontmgr_default_linux.cc

+// 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.
+
+#include "skia/ext/fontmgr_default_linux.h"
+
+#include "third_party/skia/include/ports/SkFontConfigInterface.h"
+#include "third_party/skia/include/ports/SkFontMgr.h"
+#include "third_party/skia/include/ports/SkFontMgr_FontConfigInterface.h"
+
+namespace {
+SkFontMgr* g_default_fontmgr;

[bungeman-chromium, 2016/11/14 16:03:48]

I'm not sure if we care about global destructors here. If we do care about
global destructors it's fine to leave this as very local owning bare pointer
(with a note that it is).

[steimel, 2016/11/14 18:04:42]

I'm not sure I understand what you mean, but I've changed this to hold the sk_sp
since I'm no longer having the caller retain ownership with the unique_ptr.

+}  // namespace
+
+void SetDefaultSkiaFactory(SkFontMgr* fontmgr) {

[bungeman-chromium, 2016/11/14 16:03:48]

Since this is taking ownership, this should take an sk_sp<SkFontMgr>.

We're still updating the Skia API to std::unique_ptr and sk_sp (for shared
ownership) and haven't quite gotten to the SkFontMgr interface yet, but since
this is nice and self contained it would be good to state the ownership
explicitly since we can.

[steimel, 2016/11/14 18:04:42]

Done.

+  g_default_fontmgr = fontmgr;
+}
+
+SK_API SkFontMgr* SkFontMgr::Factory() {
+  if (g_default_fontmgr) {
+    return g_default_fontmgr;
+  }
+  sk_sp<SkFontConfigInterface> fci(SkFontConfigInterface::RefGlobal());
+  return fci ? SkFontMgr_New_FCI(std::move(fci)) : nullptr;
+}