Use FastMallocPartition for BidiCharacterRun

Previously, BidiCharacterRun used LayoutPartition, which is not thread
safe. GIven that now OffscreenCanvas can render text in a thread, those
runs need to be allocated/deleted from different threads.

Tested performance was neutral.

Bug: 799362
Change-Id: Id8766e23d4be1a41effeeb8956fa1b3e06dc49a3
Reviewed-on: https://chromium-review.googlesource.com/953331
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541858}

third_party/WebKit/Source/platform/BUILD.gn

@@ -1378,7 +1378,6 @@ jumbo_component("platform") {
     "speech/PlatformSpeechSynthesisVoice.h",
     "speech/PlatformSpeechSynthesizer.cpp",
     "speech/PlatformSpeechSynthesizer.h",
-    "text/BidiCharacterRun.cpp",
     "text/BidiCharacterRun.h",
     "text/BidiContext.cpp",
     "text/BidiContext.h",

third_party/WebKit/Source/platform/text/BidiCharacterRun.cpp

-/**
- * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
- *           (C) 1999 Antti Koivisto (koivisto@kde.org)
- * Copyright (C) 2003, 2004, 2005, 2006, 2010 Apple Inc. All rights reserved.
- * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public License
- * along with this library; see the file COPYING.LIB.  If not, write to
- * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
- * Boston, MA 02110-1301, USA.
- *
- */
-
-#include "platform/text/BidiCharacterRun.h"
-
-#include "platform/wtf/allocator/Partitions.h"
-
-namespace blink {
-void* BidiCharacterRun::operator new(size_t sz) {
-  return WTF::Partitions::LayoutPartition()->Alloc(
-      sz, WTF_HEAP_PROFILER_TYPE_NAME(BidiCharacterRun));
-}
-
-void BidiCharacterRun::operator delete(void* ptr) {
-  WTF::PartitionFree(ptr);
-}
-
-}  // namespace blink

third_party/WebKit/Source/platform/text/BidiCharacterRun.h

@@ -28,6 +28,9 @@
 namespace blink {
 
 struct BidiCharacterRun {
+  USING_FAST_MALLOC(BidiCharacterRun);
+
+ public:
   BidiCharacterRun(bool override,
                    unsigned char level,
                    int start,
@@ -67,10 +70,6 @@ struct BidiCharacterRun {
         start_(start),
         stop_(stop) {}
 
-  // BidiCharacterRun are allocated out of the rendering partition.
-  PLATFORM_EXPORT void* operator new(size_t);
-  PLATFORM_EXPORT void operator delete(void*);
-
   int Start() const { return start_; }
   int Stop() const { return stop_; }
   unsigned char Level() const { return level_; }