Unmounts volumes before writing to a drive.

chrome/browser/extensions/api/image_writer_private/operation_manager.cc

Index: chrome/browser/extensions/api/image_writer_private/operation_manager.cc
diff --git a/chrome/browser/extensions/api/image_writer_private/operation_manager.cc b/chrome/browser/extensions/api/image_writer_private/operation_manager.cc
index f87f8ccbf7fe82ab6dc9a5ecd980cf9e588a0257..079125cf37031832a2b378a79c138aa8c223ce20 100644
--- a/chrome/browser/extensions/api/image_writer_private/operation_manager.cc
+++ b/chrome/browser/extensions/api/image_writer_private/operation_manager.cc
@@ -64,9 +64,14 @@ void OperationManager::StartWriteFromUrl(
     const std::string& hash,
     const std::string& device_path,
     const Operation::StartWriteCallback& callback) {
+#if defined(OS_CHROMEOS)
+  // Chrome OS can only support a single operation at a time.
+  if (operations_.size() > 0) {
+#else
   OperationMap::iterator existing_operation = operations_.find(extension_id);
 
   if (existing_operation != operations_.end()) {
+#endif
     return callback.Run(false, error::kOperationAlreadyInProgress);
   }
 
@@ -89,9 +94,14 @@ void OperationManager::StartWriteFromFile(
     const base::FilePath& path,
     const std::string& device_path,
     const Operation::StartWriteCallback& callback) {
+#if defined(OS_CHROMEOS)
+  // Chrome OS can only support a single operation at a time.
+  if (operations_.size() > 0) {
+#else
   OperationMap::iterator existing_operation = operations_.find(extension_id);
 
   if (existing_operation != operations_.end()) {
+#endif
     return callback.Run(false, error::kOperationAlreadyInProgress);
   }