libgui: Remove RefBase from BitTube

Removes RefBase from BitTube, since because it is not a Binder object,
it doesn't need to be reference-counted in this way.

In the process, we rename IDisplayEventConnection::getDataChannel to
IDEC::stealReceiveChannel to make it clearer that this is a non-const
operation on the remote end that removes its access to the receive
channel.

This also adds a couple of methods for moving the receive file
descriptor out of one BitTube and into another, since this is the
essence of the IDisplayEventConnection::stealReceiveChannel method,
and now with C++11 move semantics, we can do this without needing to
return an sp<> from EventThread's implementation of stealReceiveChannel.

Test: m -j + manual testing
Change-Id: Ibaaca2a14fb6155052fe5434c14bc3e671b43743
diff --git a/services/surfaceflinger/EventThread.cpp b/services/surfaceflinger/EventThread.cpp
index 2d3515e..a9bb2ba 100644
--- a/services/surfaceflinger/EventThread.cpp
+++ b/services/surfaceflinger/EventThread.cpp
@@ -21,7 +21,6 @@
 
 #include <cutils/compiler.h>
 
-#include <private/gui/BitTube.h>
 #include <gui/IDisplayEventConnection.h>
 #include <gui/DisplayEventReceiver.h>
 
@@ -389,7 +388,7 @@
 
 EventThread::Connection::Connection(
         const sp<EventThread>& eventThread)
-    : count(-1), mEventThread(eventThread), mChannel(new gui::BitTube(gui::BitTube::DefaultSize))
+    : count(-1), mEventThread(eventThread), mChannel(gui::BitTube::DefaultSize)
 {
 }
 
@@ -403,8 +402,8 @@
     mEventThread->registerDisplayEventConnection(this);
 }
 
-status_t EventThread::Connection::getDataChannel(sp<gui::BitTube>* outChannel) const {
-    *outChannel = mChannel;
+status_t EventThread::Connection::stealReceiveChannel(gui::BitTube* outChannel) {
+    outChannel->setReceiveFd(mChannel.moveReceiveFd());
     return NO_ERROR;
 }
 
@@ -419,7 +418,7 @@
 
 status_t EventThread::Connection::postEvent(
         const DisplayEventReceiver::Event& event) {
-    ssize_t size = DisplayEventReceiver::sendEvents(mChannel, &event, 1);
+    ssize_t size = DisplayEventReceiver::sendEvents(&mChannel, &event, 1);
     return size < 0 ? status_t(size) : status_t(NO_ERROR);
 }
 
diff --git a/services/surfaceflinger/EventThread.h b/services/surfaceflinger/EventThread.h
index 3e05749..6a59fbb 100644
--- a/services/surfaceflinger/EventThread.h
+++ b/services/surfaceflinger/EventThread.h
@@ -20,6 +20,7 @@
 #include <stdint.h>
 #include <sys/types.h>
 
+#include <private/gui/BitTube.h>
 #include <gui/DisplayEventReceiver.h>
 #include <gui/IDisplayEventConnection.h>
 
@@ -68,11 +69,11 @@
     private:
         virtual ~Connection();
         virtual void onFirstRef();
-        status_t getDataChannel(sp<gui::BitTube>* outChannel) const override;
+        status_t stealReceiveChannel(gui::BitTube* outChannel) override;
         status_t setVsyncRate(uint32_t count) override;
         void requestNextVsync() override;    // asynchronous
         sp<EventThread> const mEventThread;
-        sp<gui::BitTube> const mChannel;
+        gui::BitTube mChannel;
     };
 
 public:
diff --git a/services/surfaceflinger/MessageQueue.cpp b/services/surfaceflinger/MessageQueue.cpp
index 6ef26fe..bca3430 100644
--- a/services/surfaceflinger/MessageQueue.cpp
+++ b/services/surfaceflinger/MessageQueue.cpp
@@ -25,7 +25,6 @@
 #include <utils/Log.h>
 
 #include <gui/IDisplayEventConnection.h>
-#include <private/gui/BitTube.h>
 
 #include "MessageQueue.h"
 #include "EventThread.h"
@@ -94,8 +93,8 @@
 {
     mEventThread = eventThread;
     mEvents = eventThread->createEventConnection();
-    mEvents->getDataChannel(&mEventTube);
-    mLooper->addFd(mEventTube->getFd(), 0, Looper::EVENT_INPUT,
+    mEvents->stealReceiveChannel(&mEventTube);
+    mLooper->addFd(mEventTube.getFd(), 0, Looper::EVENT_INPUT,
             MessageQueue::cb_eventReceiver, this);
 }
 
@@ -150,7 +149,7 @@
 int MessageQueue::eventReceiver(int /*fd*/, int /*events*/) {
     ssize_t n;
     DisplayEventReceiver::Event buffer[8];
-    while ((n = DisplayEventReceiver::getEvents(mEventTube, buffer, 8)) > 0) {
+    while ((n = DisplayEventReceiver::getEvents(&mEventTube, buffer, 8)) > 0) {
         for (int i=0 ; i<n ; i++) {
             if (buffer[i].header.type == DisplayEventReceiver::DISPLAY_EVENT_VSYNC) {
                 mHandler->dispatchInvalidate();
diff --git a/services/surfaceflinger/MessageQueue.h b/services/surfaceflinger/MessageQueue.h
index 2bb5fa6..85a33c8 100644
--- a/services/surfaceflinger/MessageQueue.h
+++ b/services/surfaceflinger/MessageQueue.h
@@ -25,6 +25,7 @@
 #include <utils/Timers.h>
 #include <utils/Looper.h>
 
+#include <private/gui/BitTube.h>
 #include <gui/DisplayEventReceiver.h>
 
 #include "Barrier.h"
@@ -81,7 +82,7 @@
     sp<Looper> mLooper;
     sp<EventThread> mEventThread;
     sp<IDisplayEventConnection> mEvents;
-    sp<gui::BitTube> mEventTube;
+    gui::BitTube mEventTube;
     sp<Handler> mHandler;