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

This is a reland of cdcb0262, which was
reverted pending a fix for an underlying Mojo message-loss issue on
channel shutdown.

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: rockot
Bug: 816620
Change-Id: Ifdf10581091be31a6c9d1aa53542f2ed6c2ccbfa
Reviewed-on: https://chromium-review.googlesource.com/958016Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542650}

ipc/ipc_mojo_bootstrap_unittest.cc

@@ -55,7 +55,7 @@ class PeerPidReceiver : public IPC::mojom::Channel {
   enum class MessageExpectation {
     kNotExpected,
     kExpectedValid,
-    kExptectedInvalid
+    kExpectedInvalid
   };
 
   PeerPidReceiver(
@@ -65,7 +65,11 @@ 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 {}
+  ~PeerPidReceiver() override {
+    bool expected_message =
+        message_expectation_ != MessageExpectation::kNotExpected;
+    EXPECT_EQ(expected_message, received_message_);
+  }
 
   // mojom::Channel:
   void SetPeerPid(int32_t pid) override {
@@ -77,6 +81,7 @@ 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()));
@@ -97,6 +102,8 @@ class PeerPidReceiver : public IPC::mojom::Channel {
   MessageExpectation message_expectation_;
   int32_t peer_pid_ = -1;
 
+  bool received_message_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(PeerPidReceiver);
 };
 
@@ -140,7 +147,7 @@ TEST_F(IPCMojoBootstrapTest, ReceiveEmptyMessage) {
 
   base::RunLoop run_loop;
   PeerPidReceiver impl(std::move(receiver), run_loop.QuitClosure(),
-                       PeerPidReceiver::MessageExpectation::kExptectedInvalid);
+                       PeerPidReceiver::MessageExpectation::kExpectedInvalid);
   run_loop.Run();
 
   EXPECT_TRUE(helper_.WaitForChildTestShutdown());