net: Implement canceling of all async operations in FileStream.

base/platform_file_win.cc

Index: base/platform_file_win.cc
===================================================================
--- base/platform_file_win.cc	(revision 151422)
+++ base/platform_file_win.cc	(working copy)
@@ -113,6 +113,21 @@
   return (CloseHandle(file) != 0);
 }
 
+int64 SeekPlatformFile(PlatformFile file,
+                       PlatformFileWhence whence,
+                       int64 offset) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  if (file < 0 || offset < 0)
+    return -1;
+
+  LARGE_INTEGER distance, res;
+  distance.QuadPart = offset;
+  DWORD move_method = static_cast<DWORD>(whence);
+  if (!SetFilePointerEx(file_, distance, &res, move_method))
+    return -1;
+  return res.QuadPart;
+}
+
 int ReadPlatformFile(PlatformFile file, int64 offset, char* data, int size) {
   base::ThreadRestrictions::AssertIOAllowed();
   if (file == kInvalidPlatformFileValue)
@@ -143,6 +158,11 @@
   return ReadPlatformFile(file, offset, data, size);
 }
 
+int ReadPlatformFileCurPosNoBestEffort(PlatformFile file,
+                                       char* data, int size) {
+  return ReadPlatformFile(file, 0, data, size);
+}
+
 int WritePlatformFile(PlatformFile file, int64 offset,
                       const char* data, int size) {
   base::ThreadRestrictions::AssertIOAllowed();
@@ -168,6 +188,11 @@
   return WritePlatformFile(file, 0, data, size);
 }
 
+int WritePlatformFileCurPosNoBestEffort(PlatformFile file,
+                                        const char* data, int size) {
+  return WritePlatformFile(file, 0, data, size);
+}
+
 bool TruncatePlatformFile(PlatformFile file, int64 length) {
   base::ThreadRestrictions::AssertIOAllowed();
   if (file == kInvalidPlatformFileValue)