Revert "Add missing message-received expectation to IPCMojoBootstrapTest."

This reverts commit cdcb0262.

Reason for revert: We believe that this causes the tests to flake on various platforms, due to issue 816620. We'll re-land it when the mojo::edk::Channel fix has landed.


Original change's description:
> Add missing message-received expectation to IPCMojoBootstrapTest.
> 
> Some of these tests expected a message from the child process, and would
> verify that it was valid/invalid as expected, but would still pass if
> no message were received at all.
> 
> Bug: 816620
> Change-Id: Ie8acf85086f4416c7023118673c40d00a2e190d7
> Reviewed-on: https://chromium-review.googlesource.com/955554
> Reviewed-by: Ken Rockot <rockot@chromium.org>
> Commit-Queue: Wez <wez@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#542296}

TBR=wez@chromium.org,rockot@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 816620
Change-Id: I534fa23c12072cf08507ed4c8073e7505edaf262
Reviewed-on: https://chromium-review.googlesource.com/959241Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542526}

ipc/ipc_mojo_bootstrap_unittest.cc

@@ -65,11 +65,7 @@ class PeerPidReceiver : public IPC::mojom::Channel {
       : binding_(this, std::move(request)),
         on_peer_pid_set_(on_peer_pid_set),
         message_expectation_(message_expectation) {}
-  ~PeerPidReceiver() override {
-    bool expected_message =
-        message_expectation_ != MessageExpectation::kNotExpected;
-    EXPECT_EQ(expected_message, received_message_);
-  }
+  ~PeerPidReceiver() override {}
 
   // mojom::Channel:
   void SetPeerPid(int32_t pid) override {
@@ -81,7 +77,6 @@ class PeerPidReceiver : public IPC::mojom::Channel {
                base::Optional<std::vector<mojo::native::SerializedHandlePtr>>
                    handles) override {
     ASSERT_NE(MessageExpectation::kNotExpected, message_expectation_);
-    received_message_ = true;
 
     IPC::Message message(reinterpret_cast<const char*>(data.data()),
                          static_cast<uint32_t>(data.size()));
@@ -102,8 +97,6 @@ class PeerPidReceiver : public IPC::mojom::Channel {
   MessageExpectation message_expectation_;
   int32_t peer_pid_ = -1;
 
-  bool received_message_ = false;
-
   DISALLOW_COPY_AND_ASSIGN(PeerPidReceiver);
 };