Slay dead PayloadDecoderBaseTest::frame_header().

This CL lands server change 188737435 by clshepherd.

BUG=488484

Change-Id: Iaea875815b0de8713b72b1e7b9773a5bfff029f7
Reviewed-on: https://chromium-review.googlesource.com/974133
Commit-Queue: Bence Béky <bnc@chromium.org>
Reviewed-by: Bence Béky <bnc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545065}

net/http2/decoder/payload_decoders/payload_decoder_base_test_util.h

@@ -61,11 +61,6 @@ class PayloadDecoderBaseTest : public RandomDecoderTest {
     frame_header_is_set_ = true;
   }
 
-  const Http2FrameHeader& frame_header() const {
-    CHECK(frame_header_is_set_);
-    return frame_header_;
-  }
-
   FrameDecoderState* mutable_state() { return &frame_decoder_state_; }
 
   // Randomize the payload decoder, sets the payload decoder's frame_header_,