[fsp] Do not allow write operations on read only file systems.

chrome/browser/chromeos/file_system_provider/operations/truncate_unittest.cc

Index: chrome/browser/chromeos/file_system_provider/operations/truncate_unittest.cc
diff --git a/chrome/browser/chromeos/file_system_provider/operations/truncate_unittest.cc b/chrome/browser/chromeos/file_system_provider/operations/truncate_unittest.cc
index 66e2adcbede4aaa307cd7550bdedaaf83f223650..1ba6a14c29f743934b8957fc66f7c6411113fcf4 100644
--- a/chrome/browser/chromeos/file_system_provider/operations/truncate_unittest.cc
+++ b/chrome/browser/chromeos/file_system_provider/operations/truncate_unittest.cc
@@ -108,6 +108,29 @@ TEST_F(FileSystemProviderOperationsTruncateTest, Execute_NoListener) {
   EXPECT_FALSE(truncate.Execute(kRequestId));
 }
 
+TEST_F(FileSystemProviderOperationsTruncateTest, Execute_ReadOnly) {
+  util::LoggingDispatchEventImpl dispatcher(false /* dispatch_reply */);
+  util::StatusCallbackLog callback_log;
+
+  const ProvidedFileSystemInfo read_only_file_system_info(
+      kExtensionId,
+      kFileSystemId,
+      "" /* file_system_name */,
+      false /* writable */,
+      base::FilePath() /* mount_path */);
+
+  Truncate truncate(NULL,
+                    file_system_info_,
+                    base::FilePath::FromUTF8Unsafe(kFilePath),
+                    kTruncateLength,
+                    base::Bind(&util::LogStatusCallback, &callback_log));
+  truncate.SetDispatchEventImplForTesting(
+      base::Bind(&util::LoggingDispatchEventImpl::OnDispatchEventImpl,
+                 base::Unretained(&dispatcher)));
+
+  EXPECT_FALSE(truncate.Execute(kRequestId));
+}
+
 TEST_F(FileSystemProviderOperationsTruncateTest, OnSuccess) {
   util::LoggingDispatchEventImpl dispatcher(true /* dispatch_reply */);
   util::StatusCallbackLog callback_log;