Add extension permissions for Media Gallery API.

chrome/browser/extensions/api/media_gallery/media_gallery_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_gallery/media_gallery_api.h"
 
 #include <string>
 #include <vector>
@@ skipping 34 matching lines @@
     const FilePath& path = fsid_and_path.second;
 
     base::DictionaryValue* dict_value = new base::DictionaryValue();
     dict_value->SetWithoutPathExpansion(
         "fsid", Value::CreateStringValue(fsid));
     // The directory name is not exposed to the js layer.
     dict_value->SetWithoutPathExpansion(
         "dirname", Value::CreateStringValue("_"));
     list->Append(dict_value);
 
-    content::ChildProcessSecurityPolicy* policy =
-        ChildProcessSecurityPolicy::GetInstance();
-    if (!policy->CanReadFile(child_id, path))
-      policy->GrantReadFile(child_id, path);
-    policy->GrantReadFileSystem(child_id, fsid);
+
+    if (GetExtension()->HasAPIPermission(
+            extensions::APIPermission::kMediaGalleriesRead)) {
+      content::ChildProcessSecurityPolicy* policy =
+          ChildProcessSecurityPolicy::GetInstance();
+      if (!policy->CanReadFile(child_id, path))
+        policy->GrantReadFile(child_id, path);
+      policy->GrantReadFileSystem(child_id, fsid);
+    }

[Matt Perry, 2012/07/24 00:21:07]

What happens if the extension doesn't have read permission? Should we return an
error?

[vandebo (ex-Chrome), 2012/07/24 00:32:57]

It's an implementation detail that we could get here with the MediaGalleries
permission.  Only the MediaGalleriesRead/Write/Append permission should be
specified by extensions. If there's a cleaner way to do that then the implied
permission I've used here, I'd be happy to hear about it.  But given all that,
I'm happy to add an error case if only mediaGalleries is specified.

[Matt Perry, 2012/07/24 00:51:20]

But an extension could get here by only requesting the mediaGalleriesWrite
permission? Is calling this method an error in that case?

[vandebo (ex-Chrome), 2012/07/24 01:07:59]

Correct.  That's not an error.  But right now, only Read is defined, Write, and
Append will get defined later.

+    // TODO(vandebo) Handle write permission.
   }
 
   SetResult(list);
   return true;
 }
 
 OpenMediaGalleryManagerFunction::~OpenMediaGalleryManagerFunction() {}
 
 bool OpenMediaGalleryManagerFunction::RunImpl() {
   // TODO(vandebo) Open the Media Gallery Manager UI.
   SetResult(Value::CreateNullValue());
   return true;
 }
 
 AssembleMediaFileFunction::~AssembleMediaFileFunction() {}
 
 bool AssembleMediaFileFunction::RunImpl() {
   // TODO(vandebo) Update the metadata and return the new file.
   SetResult(Value::CreateNullValue());
   return true;
 }
 
 }  // namespace extensions