Fix a crash in the FileSystem API when the app window closes during a call.

chrome/browser/extensions/api/file_system/file_system_api.cc

Index: chrome/browser/extensions/api/file_system/file_system_api.cc
diff --git a/chrome/browser/extensions/api/file_system/file_system_api.cc b/chrome/browser/extensions/api/file_system/file_system_api.cc
index a6e91cb30de3808c4a33d1f60025fa35fbdee455..ebd1c4724f24339e446579ac62aef7ccb17d7592 100644
--- a/chrome/browser/extensions/api/file_system/file_system_api.cc
+++ b/chrome/browser/extensions/api/file_system/file_system_api.cc
@@ -164,6 +164,7 @@ bool ValidateFileEntryAndGetPath(
   // filesystem.
   content::ChildProcessSecurityPolicy* policy =
       content::ChildProcessSecurityPolicy::GetInstance();
+  DCHECK(render_view_host);

[benwells, 2013/09/10 00:47:14]

Why add all these DCHECKs?

[Sam McNally, 2013/09/10 01:04:13]

No real reason.

   if (!policy->CanReadFileSystem(render_view_host->GetProcess()->GetID(),
                                  filesystem_id)) {
     *error = kSecurityError;
@@ -339,6 +340,8 @@ void FileSystemEntryFunction::CheckWritableFiles(
 void FileSystemEntryFunction::RegisterFileSystemsAndSendResponse(
     const std::vector<base::FilePath>& paths) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  if (!render_view_host_)
+    return;
 
   CreateResponse();
   for (std::vector<base::FilePath>::const_iterator it = paths.begin();
@@ -361,6 +364,7 @@ void FileSystemEntryFunction::AddEntryToResponse(
     const base::FilePath& path,
     const std::string& id_override) {
   DCHECK(response_);
+  DCHECK(render_view_host_);
   extensions::app_file_handler_util::GrantedFileEntry file_entry =
       extensions::app_file_handler_util::CreateFileEntry(
           profile(),
@@ -451,6 +455,7 @@ bool FileSystemIsWritableEntryFunction::RunImpl() {
 
   content::ChildProcessSecurityPolicy* policy =
       content::ChildProcessSecurityPolicy::GetInstance();
+  DCHECK(render_view_host_);
   int renderer_id = render_view_host_->GetProcess()->GetID();
   bool is_writable = policy->CanReadWriteFileSystem(renderer_id,
                                                     filesystem_id);