Fix media galleries crash when the window is closed with config dialog open.

chrome/browser/extensions/api/media_galleries/media_galleries_api.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Implements the Chrome Extensions Media Galleries API.
 
 #include "chrome/browser/extensions/api/media_galleries/media_galleries_api.h"
 
 #include <set>
 #include <string>
@@ skipping 30 matching lines @@
 namespace MediaGalleries = extensions::api::media_galleries;
 namespace GetMediaFileSystems = MediaGalleries::GetMediaFileSystems;
 
 namespace extensions {
 
 namespace {
 
 const char kDisallowedByPolicy[] =
     "Media Galleries API is disallowed by policy: ";
 const char kInvalidInteractive[] = "Unknown value for interactive.";
+const char kInvalidRPH[] = "The render process no longer exists.";
 
 // Checks whether the MediaGalleries API is currently accessible (it may be
 // disallowed even if an extension has the requisite permission).
 bool ApiIsAccessible(std::string* error) {
   if (!ChromeSelectFilePolicy::FileSelectDialogsAllowed()) {
     *error = std::string(kDisallowedByPolicy) +
         prefs::kAllowFileSelectionDialogs;
     return false;
   }
 
@@ skipping 53 matching lines @@
 }
 
 void MediaGalleriesGetMediaFileSystemsFunction::GetAndReturnGalleries() {
   MediaFileSystemRegistry::GetInstance()->GetMediaFileSystemsForExtension(
       render_view_host(), GetExtension(), base::Bind(
           &MediaGalleriesGetMediaFileSystemsFunction::ReturnGalleries, this));
 }
 
 void MediaGalleriesGetMediaFileSystemsFunction::ReturnGalleries(
     const std::vector<MediaFileSystemInfo>& filesystems) {
-  const int child_id = render_view_host()->GetProcess()->GetID();
+  content::RenderViewHost* rvh = render_view_host();
+  if (!rvh) {
+    error_ = kInvalidRPH;

[asargent_no_longer_on_chrome, 2012/10/16 23:01:47]

If the RPH no longer exists, doesn't that mean it's not around to get the error
message in its callback anyway? If so then it's probably fine to omit setting
the error_ member (but we should still call SendResponse, to free up any
resources in the API dispatching system).

[vandebo (ex-Chrome), 2012/10/16 23:17:28]

Yea, I wasn't sure about that part.  Looking into it further,
UIThreadExtensionFunction::SendResponse doesn't call SendResponseImpl, which is
where error_ is consumed, so there's no need to set it.

Furthermore, that code assumes that if the rvh is valid, the rph will be valid
too, so I'm removing the rph check.

+    SendResponse(false);
+    return;
+  }
+  content::RenderProcessHost* rph = rvh->GetProcess();
+  if (!rph) {
+    error_ = kInvalidRPH;
+    SendResponse(false);
+    return;
+  }
+  const int child_id = rph->GetID();
   std::set<std::string> file_system_names;
   base::ListValue* list = new base::ListValue();
   for (size_t i = 0; i < filesystems.size(); i++) {
     scoped_ptr<base::DictionaryValue> file_system_dict_value(
         new base::DictionaryValue());
 
     // Send the file system id so the renderer can create a valid FileSystem
     // object.
     file_system_dict_value->SetWithoutPathExpansion(
         "fsid", Value::CreateStringValue(filesystems[i].fsid));
@@ skipping 54 matching lines @@
 bool MediaGalleriesAssembleMediaFileFunction::RunImpl() {
   if (!ApiIsAccessible(&error_))
     return false;
 
   // TODO(vandebo) Update the metadata and return the new file.
   SetResult(Value::CreateNullValue());
   return true;
 }
 
 }  // namespace extensions