Make base:ReplaceFile return an informative error.

base/platform_file_win.cc

Index: base/platform_file_win.cc
diff --git a/base/platform_file_win.cc b/base/platform_file_win.cc
index 2d25d3327c45bcfe53c5059be9b7105d4f2dc85e..6d4440245601bdecfaba17f2bee1feb50b44a078 100644
--- a/base/platform_file_win.cc
+++ b/base/platform_file_win.cc
@@ -90,51 +90,8 @@ PlatformFile CreatePlatformFileUnsafe(const FilePath& name,
   if (error) {
     if (file != kInvalidPlatformFileValue)
       *error = PLATFORM_FILE_OK;
-    else {
-      DWORD last_error = GetLastError();
-      switch (last_error) {
-        case ERROR_SHARING_VIOLATION:
-          *error = PLATFORM_FILE_ERROR_IN_USE;
-          break;
-        case ERROR_FILE_EXISTS:
-          *error = PLATFORM_FILE_ERROR_EXISTS;
-          break;
-        case ERROR_FILE_NOT_FOUND:
-        case ERROR_PATH_NOT_FOUND:
-          *error = PLATFORM_FILE_ERROR_NOT_FOUND;
-          break;
-        case ERROR_ACCESS_DENIED:
-          *error = PLATFORM_FILE_ERROR_ACCESS_DENIED;
-          break;
-        case ERROR_TOO_MANY_OPEN_FILES:
-          *error = PLATFORM_FILE_ERROR_TOO_MANY_OPENED;
-          break;
-        case ERROR_OUTOFMEMORY:
-        case ERROR_NOT_ENOUGH_MEMORY:
-          *error = PLATFORM_FILE_ERROR_NO_MEMORY;
-          break;
-        case ERROR_HANDLE_DISK_FULL:
-        case ERROR_DISK_FULL:
-        case ERROR_DISK_RESOURCES_EXHAUSTED:
-          *error = PLATFORM_FILE_ERROR_NO_SPACE;
-          break;
-        case ERROR_USER_MAPPED_FILE:
-          *error = PLATFORM_FILE_ERROR_INVALID_OPERATION;
-          break;
-        case ERROR_NOT_READY:
-        case ERROR_SECTOR_NOT_FOUND:
-        case ERROR_DEV_NOT_EXIST:
-        case ERROR_IO_DEVICE:
-        case ERROR_FILE_CORRUPT:
-        case ERROR_DISK_CORRUPT:
-          *error = PLATFORM_FILE_ERROR_IO;
-          break;
-        default:
-          UMA_HISTOGRAM_SPARSE_SLOWLY("PlatformFile.UnknownCreateFileErrors",
-                                      last_error);
-          *error = PLATFORM_FILE_ERROR_FAILED;
-      }
-    }
+    else
+      *error = LastErrorToPlatformFileError(GetLastError());
   }
 
   return file;
@@ -299,4 +256,40 @@ bool GetPlatformFileInfo(PlatformFile file, PlatformFileInfo* info) {
   return true;
 }
 
+PlatformFileError LastErrorToPlatformFileError(DWORD last_error) {
+  switch (last_error) {
+    case ERROR_SHARING_VIOLATION:
+      return PLATFORM_FILE_ERROR_IN_USE;
+    case ERROR_FILE_EXISTS:
+      return PLATFORM_FILE_ERROR_EXISTS;
+    case ERROR_FILE_NOT_FOUND:
+    case ERROR_PATH_NOT_FOUND:
+      return PLATFORM_FILE_ERROR_NOT_FOUND;
+    case ERROR_ACCESS_DENIED:
+      return PLATFORM_FILE_ERROR_ACCESS_DENIED;
+    case ERROR_TOO_MANY_OPEN_FILES:
+      return PLATFORM_FILE_ERROR_TOO_MANY_OPENED;
+    case ERROR_OUTOFMEMORY:
+    case ERROR_NOT_ENOUGH_MEMORY:
+      return PLATFORM_FILE_ERROR_NO_MEMORY;
+    case ERROR_HANDLE_DISK_FULL:
+    case ERROR_DISK_FULL:
+    case ERROR_DISK_RESOURCES_EXHAUSTED:
+      return PLATFORM_FILE_ERROR_NO_SPACE;
+    case ERROR_USER_MAPPED_FILE:
+      return PLATFORM_FILE_ERROR_INVALID_OPERATION;
+    case ERROR_NOT_READY:
+    case ERROR_SECTOR_NOT_FOUND:
+    case ERROR_DEV_NOT_EXIST:
+    case ERROR_IO_DEVICE:
+    case ERROR_FILE_CORRUPT:
+    case ERROR_DISK_CORRUPT:
+      return PLATFORM_FILE_ERROR_IO;
+    default:
+      UMA_HISTOGRAM_SPARSE_SLOWLY("PlatformFile.UnknownCreateFileErrors",
+                                  last_error);
+      return PLATFORM_FILE_ERROR_FAILED;
+  }
+}
+
 }  // namespace base