libgui: Normalize IDisplayEventConnection methods

This change modifies the IDisplayEventConnection API such that every
synchronous method returns a status_t (to be able to return transport
errors). This required changing getDataChannel to return its channel by
output parameter rather than return type.

Currently no more error messages are checked than before, but this will
both enable calling code to check error messages if it desires and,
more importantly, allow the Bp/Bn code to be semi-automatically
generated using SafeInterface.

Test: libgui_tests + manual testing
Change-Id: I8d5bc5ef0475cee07b638a97079b234f0384c022

1 files changed, 5 insertions, 3 deletions

diff --git a/services/surfaceflinger/EventThread.cpp b/services/surfaceflinger/EventThread.cpp
index 486bce4930..463e60c08b 100644
--- a/services/surfaceflinger/EventThread.cpp
+++ b/services/surfaceflinger/EventThread.cpp
@@ -403,12 +403,14 @@ void EventThread::Connection::onFirstRef() {
     mEventThread->registerDisplayEventConnection(this);
 }
 
-sp<BitTube> EventThread::Connection::getDataChannel() const {
-    return mChannel;
+status_t EventThread::Connection::getDataChannel(sp<BitTube>* outChannel) const {
+    *outChannel = mChannel;
+    return NO_ERROR;
 }
 
-void EventThread::Connection::setVsyncRate(uint32_t count) {
+status_t EventThread::Connection::setVsyncRate(uint32_t count) {
     mEventThread->setVsyncRate(count, this);
+    return NO_ERROR;
 }
 
 void EventThread::Connection::requestNextVsync() {