Standardize usage of virtual/override/final specifiers in ipc/.

The Google C++ style guide states:

  Explicitly annotate overrides of virtual functions or virtual
  destructors with an override or (less frequently) final specifier.
  Older (pre-C++11) code will use the virtual keyword as an inferior
  alternative annotation. For clarity, use exactly one of override,
  final, or virtual when declaring an override.

To better conform to these guidelines, the following constructs have
been rewritten:

- if a base class has a virtual destructor, then:
    virtual ~Foo();                   ->  ~Foo() override;
- virtual void Foo() override;        ->  void Foo() override;
- virtual void Foo() override final;  ->  void Foo() final;

This patch was automatically generated. The clang plugin can generate
fixit hints, which are suggested edits when it is 100% sure it knows how
to fix a problem. The hints from the clang plugin were applied to the
source tree using the tool in https://codereview.chromium.org/598073004.

Several formatting edits by clang-format were manually reverted, due to
mangling of some of the more complicate IPC macros.

BUG=417463

Review URL: https://codereview.chromium.org/815503005

Cr-Commit-Position: refs/heads/master@{#309578}

ipc/ipc_channel.h

@@ -178,7 +178,7 @@ class IPC_EXPORT Channel : public Sender {
   //
   // |message| must be allocated using operator new.  This object will be
   // deleted once the contents of the Message have been sent.
-  virtual bool Send(Message* message) override = 0;
+  bool Send(Message* message) override = 0;
 
   // NaCl in Non-SFI mode runs on Linux directly, and the following functions
   // compiled on Linux are also needed. Please see also comments in

ipc/ipc_channel_posix_unittest.cc

@@ -109,8 +109,8 @@ class IPCChannelPosixTest : public base::MultiProcessTest {
   static const std::string GetChannelDirName();
 
  protected:
-  virtual void SetUp();
-  virtual void TearDown();
+  void SetUp() override;
+  void TearDown() override;
 
  private:
   scoped_ptr<base::MessageLoopForIO> message_loop_;

ipc/ipc_channel_proxy_unittest.cc

@@ -232,9 +232,9 @@ class MessageCountFilter : public IPC::MessageFilter {
 class IPCChannelProxyTest : public IPCTestBase {
  public:
   IPCChannelProxyTest() {}
-  virtual ~IPCChannelProxyTest() {}
+  ~IPCChannelProxyTest() override {}
 
-  virtual void SetUp() override {
+  void SetUp() override {
     IPCTestBase::SetUp();
 
     Init("ChannelProxyClient");
@@ -250,7 +250,7 @@ class IPCChannelProxyTest : public IPCTestBase {
     ASSERT_TRUE(StartClient());
   }
 
-  virtual void TearDown() {
+  void TearDown() override {
     DestroyChannelProxy();
     thread_.reset();
     listener_.reset();

ipc/ipc_test_base.h

@@ -32,9 +32,9 @@ class IPCTestBase : public base::MultiProcessTest {
 
  protected:
   IPCTestBase();
-  virtual ~IPCTestBase();
+  ~IPCTestBase() override;
 
-  virtual void TearDown() override;
+  void TearDown() override;
 
   // Initializes the test to use the given client and creates an IO message loop
   // on the current thread.