include boringssl headers from third_party explicitly

content/DEPS

 # Do NOT add chrome to the list below. We shouldn't be including files
 # from src/chrome in src/content.
 include_rules = [
   # The subdirectories in content/ will manually allow their own include
   # directories in content/ so we disallow all of them.
   "-content",
   "+content/app/resources/grit/content_resources.h",
   "+content/common",
   "+content/grit",
   "+content/public/common",
@@ skipping 48 matching lines @@
   # don't expect alternate implementations to be provided by the
   # embedder.
   "-google_apis",
 
   # Don't allow inclusion of these other libs we shouldn't be calling directly.
   "-v8",
   "-tools",
 
   # Allow inclusion of third-party code:
   "+third_party/angle",
+  "+third_party/boringssl/src/include",
   "+third_party/flac",
   "+third_party/libjingle",
   "+third_party/mozilla",
   "+third_party/ocmock",
   "+third_party/re2",
   "+third_party/skia",
   "+third_party/sqlite",
   "+third_party/khronos",
   "+third_party/webrtc",
   "+third_party/webrtc_overrides",
@@ skipping 43 matching lines @@
   "+jni",
 ]
 
 # content -> content/shell dependency is not allowed, except for browser tests.
 specific_include_rules = {
   ".*_browsertest[a-z_]*\.(cc|h)": [
     "+content/shell/browser",
     "+content/shell/common",
   ],
 }