Add a Pepper audio basic functionality unit test.

ipc/ipc_channel.h

Index: ipc/ipc_channel.h
diff --git a/ipc/ipc_channel.h b/ipc/ipc_channel.h
index a7a9a347b3c664133d8bffd3586a07592ae91a1d..8468d7c76fec23291fe8e569b5829b3a21e3f28f 100644
--- a/ipc/ipc_channel.h
+++ b/ipc/ipc_channel.h
@@ -96,6 +96,13 @@ class Channel : public Message::Sender {
   int GetClientFileDescriptor() const;
 #endif  // defined(OS_POSIX)
 
+ protected:
+  // Used in Chrome by the TestSink to provide a dummy channel implementation
+  // for testing. TestSink overrides the "interesting" functions in Channel so
+  // no actual implementation is needed. This will cause un-overridden calls to
+  // segfault. Do not use outside of test code!
+  Channel() : channel_impl_(0) { }
+
  private:
   // PIMPL to which all channel calls are delegated.
   class ChannelImpl;