Adds USB writing for OS X.

chrome/utility/image_writer/image_writer_win.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <windows.h>
 #include <setupapi.h>
 #include <winioctl.h>
 
 #include "chrome/utility/image_writer/error_messages.h"
 #include "chrome/utility/image_writer/image_writer.h"
@@ skipping 37 matching lines @@
     PLOG(ERROR) << "Storage property query failed";
     return false;
   }
 
   STORAGE_DEVICE_DESCRIPTOR* device_descriptor =
       reinterpret_cast<STORAGE_DEVICE_DESCRIPTOR*>(output_buf.get());
 
   return device_descriptor->RemovableMedia == TRUE;
 }
 
-bool ImageWriter::UnmountVolumes() {
+bool ImageWriter::OpenDevice() {
+  // Windows requires that device files be opened with FILE_FLAG_NO_BUFFERING
+  // and FILE_FLAG_WRITE_THROUGH.  These two flags are not part of base::File.
+  device_file_ =
+      base::File(CreateFile(device_path_.value().c_str(),
+                            GENERIC_READ | GENERIC_WRITE,
+                            FILE_SHARE_READ | FILE_SHARE_WRITE,
+                            NULL,
+                            OPEN_EXISTING,
+                            FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH,
+                            NULL));
+  return device_file_.IsValid();
+}
+
+void ImageWriter::UnmountVolumes(const base::Closure& continuation) {
   if (!InitializeFiles()) {
-    return false;
+    return;
   }
 
   STORAGE_DEVICE_NUMBER sdn = {0};
   DWORD bytes_returned;
 
   BOOL status = DeviceIoControl(
       device_file_.GetPlatformFile(),
       IOCTL_STORAGE_GET_DEVICE_NUMBER,
       NULL,             // Unused, must be NULL.
       0,                // Unused, must be 0.
       &sdn,             // An input buffer to hold the STORAGE_DEVICE_NUMBER
       sizeof(sdn),      // The size of the input buffer.
       &bytes_returned,  // the actual number of bytes returned.
       NULL);            // Unused overlap.
   if (!status) {
     PLOG(ERROR) << "Unable to get device number.";
-    return false;
+    return;
   }
 
   ULONG device_number = sdn.DeviceNumber;
 
   TCHAR volume_path[MAX_PATH + 1];
   HANDLE volume_finder = FindFirstVolume(volume_path, MAX_PATH + 1);
   if (volume_finder == INVALID_HANDLE_VALUE) {
-    return false;
+    return;
   }
 
   HANDLE volume_handle;
   bool first_volume = true;
   bool success = true;
 
   while (first_volume ||
          FindNextVolume(volume_finder, volume_path, MAX_PATH + 1)) {
     first_volume = false;
 
@@ skipping 74 matching lines @@
         success = false;
         break;
       }
     }
   }
 
   if (volume_finder != INVALID_HANDLE_VALUE) {
     FindVolumeClose(volume_finder);
   }
 
-  return success;
+  if (success)
+    continuation.Run();
 }
 
 }  // namespace image_writer