Cleanup: Remove unused variables in chrome/ found by Scythe.

chrome/utility/image_writer/error_messages.cc

Index: chrome/utility/image_writer/error_messages.cc
diff --git a/chrome/utility/image_writer/error_messages.cc b/chrome/utility/image_writer/error_messages.cc
index 2847f222a063f00973438489b8a930f6fe768082..e282ff4bb62bf51cf1aeef23d17de316c9c637f6 100644
--- a/chrome/utility/image_writer/error_messages.cc
+++ b/chrome/utility/image_writer/error_messages.cc
@@ -7,18 +7,16 @@
 namespace image_writer {
 namespace error {
 
-const char kCleanUp[] = "Failed to clean up after write operation.";
-const char kCloseDevice[] = "Failed to close usb device.";
-const char kCloseImage[] = "Failed to close image file.";
 const char kInvalidDevice[] = "Invalid device path.";
-const char kNoOperationInProgress[] = "No operation in progress.";
 const char kOpenDevice[] = "Failed to open device.";
 const char kOpenImage[] = "Failed to open image.";
 const char kOperationAlreadyInProgress[] = "Operation already in progress.";
 const char kReadDevice[] = "Failed to read device.";
 const char kReadImage[] = "Failed to read image.";
 const char kWriteImage[] = "Writing image to device failed.";
+#if defined(OS_MACOSX)
 const char kUnmountVolumes[] = "Unable to unmount the device.";
+#endif
 const char kVerificationFailed[] = "Verification failed.";
 
 }  // namespace error