ART: Track Flush & Close in FdFile

Implement a check that aborts when a file hasn't been explicitly
flushed and closed when it is destructed.

Add WARN_UNUSED to FdFile methods.

Update dex2oat, patchoat, scoped_flock and some gtests to pass with
this.

(cherry picked from commit 9433ec60b325b708b9fa87e699ab4a6565741494)

Change-Id: I9ab03b1653e69f44cc98946dc89d764c3e045dd4
diff --git a/runtime/common_runtime_test.cc b/runtime/common_runtime_test.cc
index 6e3ebc2..03b33e9 100644
--- a/runtime/common_runtime_test.cc
+++ b/runtime/common_runtime_test.cc
@@ -59,7 +59,7 @@
   filename_ += "/TmpFile-XXXXXX";
   int fd = mkstemp(&filename_[0]);
   CHECK_NE(-1, fd);
-  file_.reset(new File(fd, GetFilename()));
+  file_.reset(new File(fd, GetFilename(), true));
 }
 
 ScratchFile::ScratchFile(const ScratchFile& other, const char* suffix) {
@@ -67,7 +67,7 @@
   filename_ += suffix;
   int fd = open(filename_.c_str(), O_RDWR | O_CREAT, 0666);
   CHECK_NE(-1, fd);
-  file_.reset(new File(fd, GetFilename()));
+  file_.reset(new File(fd, GetFilename(), true));
 }
 
 ScratchFile::ScratchFile(File* file) {
@@ -88,6 +88,11 @@
   if (!OS::FileExists(filename_.c_str())) {
     return;
   }
+  if (file_.get() != nullptr) {
+    if (file_->FlushCloseOrErase() != 0) {
+      PLOG(WARNING) << "Error closing scratch file.";
+    }
+  }
   int unlink_result = unlink(filename_.c_str());
   CHECK_EQ(0, unlink_result);
 }