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* Fix/add header guards in header files in //net except for in //net/third_party
  and in header files that are meant to be included only with some special macro
  defined (these are typically *_list.h):
  + #ifndef FILE_NAME in line 5,
  + #define FILE_NAME in line 6,
  + #endif  // FILE_NAME in the last line.
* Add newline to the end of files that do not already end in a newline.
* Remove empty line from the end of files that end in an empty line
  (that is, remove newline characters down to exactly one newline).
* Add empty line between Copyright notice and header guard in
  net/proxy/dhcpcsvc_init_win.h

Review-Url: https://codereview.chromium.org/2562113002
Cr-Commit-Position: refs/heads/master@{#437694}