Initialize FontConfigIPC when zygote is disabled so font fallback works.

content/browser/renderer_host/sandbox_ipc_linux.h

 // Copyright 2014 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.
 
 // https://chromium.googlesource.com/chromium/src/+/master/docs/linux_sandbox_ipc.md
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_SANDBOX_IPC_LINUX_H_
 #define CONTENT_BROWSER_RENDERER_HOST_SANDBOX_IPC_LINUX_H_
 
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "base/files/scoped_file.h"
 #include "base/macros.h"
 #include "base/pickle.h"
 #include "base/threading/simple_thread.h"
+#include "content/common/content_export.h"
+#include "third_party/icu/source/common/unicode/uchar.h"
 
 class SkString;
 
 namespace content {
 
 class SandboxIPCHandler : public base::DelegateSimpleThread::Delegate {
  public:
   // lifeline_fd: the read end of a pipe which the main thread holds
   // the other end of.
   // browser_socket: the browser's end of the sandbox IPC socketpair.
   SandboxIPCHandler(int lifeline_fd, int browser_socket);
   ~SandboxIPCHandler() override;
 
   void Run() override;
 
+  class TestObserver {
+   public:
+    virtual void OnGetFallbackFontForChar(UChar32 c,
+                                          std::string name,
+                                          int id) = 0;
+    virtual void OnFontOpen(int id) = 0;
+  };
+  CONTENT_EXPORT static void SetObserverForTests(TestObserver* observer);
+
  private:
   int FindOrAddPath(const SkString& path);
 
   void HandleRequestFromRenderer(int fd);
 
   void HandleFontMatchRequest(int fd,
                               base::PickleIterator iter,
                               const std::vector<base::ScopedFD>& fds);
 
   void HandleFontOpenRequest(int fd,
@@ skipping 27 matching lines @@
   const int lifeline_fd_;
   const int browser_socket_;
   std::vector<SkString> paths_;
 
   DISALLOW_COPY_AND_ASSIGN(SandboxIPCHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_SANDBOX_IPC_LINUX_H_