Fix compilation errors on ChromeOS

Description:
This cl fixes two compilation errors on ChromeOS/ARM, it could
also be reproduced by gcc 4.5+.

I also add comments about error message and how I solve them.

BUG=webrtc issue 554
TEST=try bots and build on chromeos arm
Review URL: https://webrtc-codereview.appspot.com/611006

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2327 4adac7df-926f-26a2-2b94-8c16560cd09d

src/modules/udp_transport/source/udp_socket_manager_unittest.cc

@@ -27,7 +27,7 @@ TEST(UdpSocketManager, CreateCallsInitAndDoesNotLeakMemory) {
   WebRtc_UWord8 threads = 1;
   UdpSocketManager* mgr = UdpSocketManager::Create(id, threads);
   // Create is supposed to have called init on the object.
-  EXPECT_EQ(false, mgr->Init(id, threads))
+  EXPECT_FALSE(mgr->Init(id, threads))
       << "Init should return false since Create is supposed to call it.";
   UdpSocketManager::Return();
 }
@@ -71,6 +71,9 @@ TEST(UdpSocketManager, UnremovedSocketsGetCollectedAtManagerDeletion) {
                                                 false,  // ipV6Enable
                                                 false);  // disableGQOS
   // The constructor will do AddSocket on the manager.
+  // Call a member funtion to work around "set but not used" compliation
+  // error on ChromeOS ARM.
+  unused_socket->SetEventToNull();
   unused_socket = NULL;
   UdpSocketManager::Return();
 #endif