Chrome Version: M64
OS: All

What steps will reproduce the problem?
(1) Modify the ExtensionProtocolsTest.ComponentResourceRequest test to read the content-type as follows:

TEST_F(ExtensionProtocolsTest, ComponentResourceRequest) {
  ...

  // First test it with the extension enabled.
  {
    ...
    std::string mime_type;
    request->GetResponseHeaderByName(net::HttpRequestHeaders::kContentType,
                                     &mime_type);
    EXPECT_EQ("image/png", mime_type);
  }

(2) Run the test

What is the expected result?

  mime_type should be "image/png"

What happens instead?

  mime_type is an empty string.

Note: This is *not* the cause of any known problem, but is probably an oversight that should be fixed.