Extract SandboxIPCProcess into its own file.

content/browser/renderer_host/DEPS

Index: content/browser/renderer_host/DEPS
diff --git a/content/browser/renderer_host/DEPS b/content/browser/renderer_host/DEPS
index e6ae4cd6127ec3db66264da04c41a9e79ca3f5a7..55a8ec5f01df7c204367db7a5742c9e3ce48b4f5 100644
--- a/content/browser/renderer_host/DEPS
+++ b/content/browser/renderer_host/DEPS
@@ -22,11 +22,13 @@ specific_include_rules = {
     "+content/public/browser/web_contents_view.h",
     "+media/filters",
   ],
-  "render_sandbox_host_linux\.cc": [
-    "+content/child/blink_platform_impl.h",
+  "sandbox_ipc_linux\.cc": [
     "+third_party/WebKit/public/platform/linux/WebFontInfo.h",
     "+third_party/WebKit/public/web/WebKit.h",
   ],
+  "sandbox_ipc_linux\.h": [
+    "+content/child/blink_platform_impl.h",
+  ],
   "render_process_host_impl\.cc": [
     "+content/browser/frame_host/render_frame_message_filter.h",
   ],