Fallback Font Cache and Character Hinting for VRShell

ui/gfx/font_fallback_android.h

Index: ui/gfx/font_fallback_android.h
diff --git a/ui/gfx/font_fallback_android.h b/ui/gfx/font_fallback_android.h
new file mode 100644
index 0000000000000000000000000000000000000000..00b68d5f81c76facdf9169f8d22abfab96d1ed90
--- /dev/null
+++ b/ui/gfx/font_fallback_android.h
@@ -0,0 +1,32 @@
+// Copyright 2017 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 UI_GFX_FONT_FALLBACK_ANDROID_H_
+#define UI_GFX_FONT_FALLBACK_ANDROID_H_
+
+#include <string>
+
+#include "third_party/icu/source/common/unicode/uchar.h"
+#include "ui/gfx/font_fallback.h"
+#include "ui/gfx/gfx_export.h"
+
+namespace gfx {
+
+// Return a font name which provides a glyph for the Unicode code point
+// specified by character.
+//   default_font: The main font for which fallbacks are required
+//   c: a UTF-32 code point
+//   preferred_locale: preferred locale identifier (if any) for |c|
+//                     (e.g. "en", "ja", "zh-CN")
+//
+// Returns: the font name. The value is empty if the request could not be
+// satisfied or if the provided default font supports it.
+GFX_EXPORT std::string GetFallbackFontNameForChar(

[Alexei Svitkine (slow), 2017/05/09 14:52:17]

If this is only used by vr_shell, why not put the implementation there?

[acondor_, 2017/05/09 16:21:51]

Because this is platform dependent code and this seemed like the most
appropriate place to put it for now. VR Shell is currently android-only, but it
will be multi-platform in the future.

[Alexei Svitkine (slow), 2017/05/09 16:40:41]

Any directory in Chrome could have platform-specific code - by using the same
convention you use here - i.e. suffixing the files with the platform name. I
don't see that as an argument for this needing to be in gfx/.

Usually code is placed at lower levels when it's used by multiple places - and
it's fine to have code more local until then and to move it later if it later
gets more than one users from other directories.

[acondor_, 2017/05/09 18:44:16]

You are right. I moved the code to vr_shell namespace but kept out the _android
suffix until we start implementing the Shell for other platforms.

+    const Font& default_font,
+    UChar32 c,
+    const std::string& preferred_locale);
+
+}  // namespace gfx
+
+#endif  // UI_GFX_FONT_FALLBACK_ANDROID_H_