Define NOVOLUME for unrar code

To prevent attempting to extract other volumes within the sandbox, this
CL puts unrar in NOVOLUME mode. I also added a quick test to ensure we
still detect the presence of files in NOVOLUME mode, so this should be
safe.

Note: The generation of multipart rar files seems a little finicky. The
following two commands worked for me.

dd if=/dev/urandom of=random.exe bs=1k count=1
rar a -v1b multipart.rar random.exe

Bug: 917679, 909778
Change-Id: I472b0e959d7538dc9136597ada631707b044e765
Reviewed-on: https://chromium-review.googlesource.com/c/1393803Reviewed-by: Jay Civelli <jcivelli@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Commit-Queue: Daniel Rubery <drubery@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620026}

chrome/services/file_util/public/cpp/sandboxed_rar_analyzer_unittest.cc

@@ -272,5 +272,19 @@ TEST_F(SandboxedRarAnalyzerTest,
 #endif
 }
 
+TEST_F(SandboxedRarAnalyzerTest, AnalyzeMultipartRarContainingExecutable) {
+  base::FilePath path;
+  // Contains one part of an exe file.
+  ASSERT_NO_FATAL_FAILURE(path = GetFilePath("multipart.part0001.rar"));
+
+  safe_browsing::ArchiveAnalyzerResults results;
+  AnalyzeFile(path, &results);
+
+  ASSERT_TRUE(results.success);
+  ASSERT_TRUE(results.has_executable);
+  EXPECT_EQ(1, results.archived_binary.size());
+  EXPECT_TRUE(results.archived_archive_filenames.empty());
+}
+
 }  // namespace
 }  // namespace safe_browsing

third_party/unrar/BUILD.gn

@@ -67,6 +67,7 @@ if (safe_browsing_mode == 1) {
       "LARGEFILE_SOURCE",
       "RAR_SMP",
       "SILENT",
+      "NOVOLUME",
 
       # The following is set to disable certain macro definitions in the unrar
       # source code.