Upstream the iOS web_shell and supporting code

ios/web/shell/shell_browser_state.h

Index: ios/web/shell/shell_browser_state.h
diff --git a/ios/web/shell/shell_browser_state.h b/ios/web/shell/shell_browser_state.h
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+// 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.
+
+#ifndef IOS_WEB_SHELL_SHELL_BROWSER_STATE_H_
+#define IOS_WEB_SHELL_SHELL_BROWSER_STATE_H_
+
+#include "ios/web/public/browser_state.h"
+
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace web {
+
+class ShellBrowserContext;
+class ShellURLRequestContextGetter;
+
+// Shell-specific implementation of BrowserState.  Can only be called from the
+// UI thread.
+class ShellBrowserState : public BrowserState {
+ public:
+  ShellBrowserState();
+  ~ShellBrowserState() override;
+
+  // BrowserState implementation.
+  bool IsOffTheRecord() const override;
+  base::FilePath GetStatePath() const override;
+  net::URLRequestContextGetter* GetRequestContext() override;
+
+ private:
+  base::FilePath path_;
+  scoped_refptr<ShellURLRequestContextGetter> request_context_getter_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShellBrowserState);
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_SHELL_SHELL_BROWSER_STATE_H_