Initialize ios/web_view translate with a system-wide URLRequestContext.

ios/web_view/internal/web_view_web_main_parts.h

Index: ios/web_view/internal/web_view_web_main_parts.h
diff --git a/ios/web_view/internal/web_view_web_main_parts.h b/ios/web_view/internal/web_view_web_main_parts.h
index 10f02796fb6fad5b8a0bfc709ff76e3faa4a94a8..51a40fa99ef91808425abc2b1302fef9b9f2989f 100644
--- a/ios/web_view/internal/web_view_web_main_parts.h
+++ b/ios/web_view/internal/web_view_web_main_parts.h
@@ -7,20 +7,35 @@
 
 #include <memory>
 
+#include "base/macros.h"
 #include "ios/web/public/app/web_main_parts.h"
 
-@protocol CWVDelegate;
+namespace base {
+class CommandLine;
+}
 
 namespace ios_web_view {
 
+class ApplicationContextImpl;
+
 // WebView implementation of WebMainParts.
 class WebViewWebMainParts : public web::WebMainParts {
  public:
-  WebViewWebMainParts();
+  explicit WebViewWebMainParts(const base::CommandLine& parsed_command_line);
   ~WebViewWebMainParts() override;
 
-  // WebMainParts implementation.
-  void PreMainMessageLoopRun() override;
+ private:
+  // web::WebMainParts implementation.
+  void PreMainMessageLoopStart() override;
+  void PreCreateThreads() override;
+  void PostMainMessageLoopRun() override;
+  void PostDestroyThreads() override;
+
+  const base::CommandLine& parsed_command_line_;
+
+  std::unique_ptr<ApplicationContextImpl> application_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebViewWebMainParts);
 };
 
 }  // namespace ios_web_view