Add a helper class that keeps per-profile information for FileSystem API

chrome/browser/profile.cc

Index: chrome/browser/profile.cc
diff --git a/chrome/browser/profile.cc b/chrome/browser/profile.cc
index 116b6457684d47cbea57d6ae172f95cba9d9a450..c3fe4197c45e597a05fbd33c70cd23a3df89e8c5 100644
--- a/chrome/browser/profile.cc
+++ b/chrome/browser/profile.cc
@@ -17,6 +17,7 @@
 #include "chrome/browser/browser_theme_provider.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/download/download_manager.h"
+#include "chrome/browser/file_system/file_system_host_context.h"
 #include "chrome/browser/find_bar_state.h"
 #include "chrome/browser/in_process_webkit/webkit_context.h"
 #include "chrome/browser/net/chrome_url_request_context.h"
@@ -313,6 +314,14 @@ class OffTheRecordProfileImpl : public Profile,
     return NULL;
   }
 
+  virtual FileSystemHostContext* GetFileSystemHostContext() {
+    if (!file_system_host_context_)
+      file_system_host_context_ = new FileSystemHostContext(
+          GetPath(), IsOffTheRecord());
+    DCHECK(file_system_host_context_.get());
+    return file_system_host_context_.get();
+  }
+
   virtual void InitThemes() {
     profile_->InitThemes();
   }
@@ -566,6 +575,9 @@ class OffTheRecordProfileImpl : public Profile,
   // Tracks all BackgroundContents running under this profile.
   scoped_ptr<BackgroundContentsService> background_contents_service_;
 
+  // The file_system context for this profile.
+  scoped_refptr<FileSystemHostContext> file_system_host_context_;
+
   DISALLOW_COPY_AND_ASSIGN(OffTheRecordProfileImpl);
 };