Convert base::MemoryMappedFile to use File instead of PlatformFile.

chrome/renderer/spellchecker/hunspell_engine.cc

Index: chrome/renderer/spellchecker/hunspell_engine.cc
diff --git a/chrome/renderer/spellchecker/hunspell_engine.cc b/chrome/renderer/spellchecker/hunspell_engine.cc
index 7900c507ad5adbfb3b62e82a2336644638070e99..b9da1659f0bb042aba95468bd41e96412f8c87a6 100644
--- a/chrome/renderer/spellchecker/hunspell_engine.cc
+++ b/chrome/renderer/spellchecker/hunspell_engine.cc
@@ -61,7 +61,9 @@ void HunspellEngine::InitializeHunspell() {
 
   bdict_file_.reset(new base::MemoryMappedFile);
 
-  if (bdict_file_->Initialize(file_)) {
+  // TODO(rvargas): This object should not keep file_ after passing it to
+  // bdict_file_.

[groby-ooo-7-16, 2013/12/27 19:52:26]

If you want to address the TODO: file_, bdict_file_, initialized_ and
dictionary_requested_ together are used to coordinate a multi-stage
initialization. Relinquishing file_ might be tricky :)

(Stages are bare object, request dictionary, memory map dictionary & init
hunspell. The last 2 are on demand, when InitializeIfNeeded is called)

+  if (bdict_file_->Initialize(base::File(file_))) {

[groby-ooo-7-16, 2013/12/27 19:52:26]

Probably want file_ to be base::File, for clearer ownership semantics. (Also,
this fixes a file leak if InitializeHunspell is never called :)

[rvargas (doing something else), 2013/12/27 23:54:39]

That sounds correct. I didn't do it because it probably means changing Init (and
the callers) to pass File instead, and I don't know what would be the logic for
IsEnabled (cannot be file_.IsValid()). Besides, I'm trying to contain the scope
of this change.

Keeping the current type for file_ at least makes clear that this code has to be
updated.

     TimeTicks debug_start_time = base::Histogram::DebugNow();
 
     hunspell_.reset(