Adds FontGlobalContext to store static objects of platform/font

Currently only being used on FontCache, to be used on other Font-related
classes.

Bug: 730692
Change-Id: I58f66d6cf59dca83be5133fc273136ce408e5b2e
Reviewed-on: https://chromium-review.googlesource.com/531753
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478802}

third_party/WebKit/Source/platform/BUILD.gn

@@ -674,6 +674,8 @@ component("platform") {
     "fonts/FontFallbackPriority.h",
     "fonts/FontFamily.cpp",
     "fonts/FontFamily.h",
+    "fonts/FontGlobalContext.cpp",
+    "fonts/FontGlobalContext.h",
     "fonts/FontMetrics.h",
     "fonts/FontOrientation.h",
     "fonts/FontPlatformData.cpp",

third_party/WebKit/Source/platform/fonts/FontCache.cpp

@@ -40,6 +40,7 @@
 #include "platform/fonts/FontCacheKey.h"
 #include "platform/fonts/FontDataCache.h"
 #include "platform/fonts/FontDescription.h"
+#include "platform/fonts/FontGlobalContext.h"
 #include "platform/fonts/FontPlatformData.h"
 #include "platform/fonts/FontSmoothingMode.h"
 #include "platform/fonts/SimpleFontData.h"
@@ -96,8 +97,7 @@ bool FontCache::use_skia_font_fallback_ = false;
 #endif  // OS(WIN)
 
 FontCache* FontCache::GetFontCache() {
-  DEFINE_STATIC_LOCAL(FontCache, global_font_cache, ());
-  return &global_font_cache;
+  return &FontGlobalContext::GetFontCache();
 }
 
 #if !OS(MACOSX)

third_party/WebKit/Source/platform/fonts/FontCache.h

@@ -61,6 +61,7 @@ namespace blink {
 
 class FontCacheClient;
 class FontFaceCreationParams;
+class FontGlobalContext;
 class FontPlatformData;
 class FontDescription;
 class OpenTypeVerticalData;
@@ -221,8 +222,8 @@ class PLATFORM_EXPORT FontCache {
   void DumpShapeResultCache(base::trace_event::ProcessMemoryDump*);
 
  private:
+  friend class FontGlobalContext;
   FontCache();
-  ~FontCache();
 
   void Purge(PurgeSeverity = kPurgeIfNeeded);
 

third_party/WebKit/Source/platform/fonts/FontGlobalContext.cpp

+// 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.
+
+#include "platform/fonts/FontGlobalContext.h"
+
+#include "platform/fonts/FontCache.h"
+#include "platform/wtf/StdLibExtras.h"
+#include "platform/wtf/ThreadSpecific.h"
+
+namespace blink {
+
+FontGlobalContext& FontGlobalContext::Get() {
+  DEFINE_THREAD_SAFE_STATIC_LOCAL(ThreadSpecific<FontGlobalContext>,
+                                  font_persistent, ());
+  return *font_persistent;
+}
+
+FontGlobalContext::FontGlobalContext() {}
+
+}  // namespace blink

third_party/WebKit/Source/platform/fonts/FontGlobalContext.h

+// 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 FontGlobalContext_h
+#define FontGlobalContext_h
+
+#include "platform/PlatformExport.h"
+#include "platform/fonts/FontCache.h"
+#include "platform/wtf/StdLibExtras.h"
+
+namespace blink {
+
+// FontGlobalContext contains non-thread-safe, thread-specific data used for
+// font formatting.
+class PLATFORM_EXPORT FontGlobalContext {
+  WTF_MAKE_NONCOPYABLE(FontGlobalContext);
+
+ public:
+  static FontGlobalContext& Get();
+
+  static inline FontCache& GetFontCache() { return Get().font_cache; }
+
+ private:
+  friend class WTF::ThreadSpecific<FontGlobalContext>;
+
+  FontGlobalContext();
+
+  FontCache font_cache;
+};
+
+}  // namespace blink
+
+#endif