Declare providing extension capabilities in the manifest.

chrome/common/extensions/api/file_system_provider.idl

Index: chrome/common/extensions/api/file_system_provider.idl
diff --git a/chrome/common/extensions/api/file_system_provider.idl b/chrome/common/extensions/api/file_system_provider.idl
index 0772f2c337a78cf5053da65f4d79d8a846b489e4..6c30f919660872cb147b26afa0853e54d97351de 100644
--- a/chrome/common/extensions/api/file_system_provider.idl
+++ b/chrome/common/extensions/api/file_system_provider.idl
@@ -41,20 +41,34 @@ namespace fileSystemProvider {
     DELETED
   };
 
-  // Source of the file system data.
-  enum FileSystemSource {
-    // The file system is handling a file, eg. an archive file obtained via the
+  // Source of data for provided file systems. Used in manifest files of
+  // providing extensions.
+  enum Source {
+    // File systems are handling files, eg. an archive file obtained via the
     // <code>onLaunched</code> event and the <code>file_handlers</code> manifest
     // entry.
-    FILE,
+    file,
 
-    // The file system contents are fetched from an external device, such as a
+    // File systems' contents are fetched from an external device, such as a
     // USB device, but not via <code>file_handlers</code>.
-    DEVICE,
+    device,
 
-    // The file system is network based. The contents are obtained from another
+    // File systems are network based. The contents are obtained from another
     // server or local network. Eg. cloud services.
-    NETWORK
+    network
+  };
+
+  // Represents capabilities of a providing extension. Used in manifest files of
+  // providing extensions.
+  dictionary Capabilities {
+    // Whether configuring via <code>onConfigureRequested</code> is supported.
+    boolean configurable;
+
+    // Whether multiple (more than one) mounted file systems are supported.
+    boolean multiple_mounts;

[not at google - send to devlin, 2015/04/23 23:16:35]

multipleMounts would be more consistent.

[mtomasz, 2015/04/24 12:16:11]

In manifest we always use underscored_keys. So we either have consistency within
manifest, or consistency with results of
fileBrowserPrivate.getProvidingExtensions(). Which one do you prefer?

[not at google - send to devlin, 2015/04/24 16:18:32]

There are plenty of counterexamples to this rule, but for better or worse, we
typically use underscores for manifest keys and camelcase for APIs. It should
really be camelcase for everything.

For an example of something where we differ in manifest and the API, see the
browser action API; the manifest keys are browser_action,
browser_action.default_title, etc; but the API uses browserAction,
browserAction.setTitle, browserAction.setTitle({imageData}), etc.

[mtomasz, 2015/04/24 17:12:10]

Well, this is exactly what I'm doing. This dictionary is used for manifest
parsing (see comment). For extensions, on JS side, camelCase is used instead,
see file_manager_private.idl.

+
+    // Source of data for all mounted file systems.
+    Source source;

[not at google - send to devlin, 2015/04/23 23:16:35]

This is now required; was that an intentional change? should there be, or does
there need to be, an "other" in the source?

[mtomasz, 2015/04/24 12:16:11]

I found the "OTHER" an overkill. Instead I decided to use a default "FILE" if
the entire "file_system_provider" section is not available. The manifest section
is optional, but all keys required if the section is declared.

   };
 
   // Represents metadata of a file or a directory.
@@ -125,9 +139,6 @@ namespace fileSystemProvider {
     // List of currently opened files.
     OpenedFile[] openedFiles;
 
-    // Source of the file system data.
-    FileSystemSource? source;
-
     // Whether the file system supports the <code>tag</code> field for observing
     // directories.
     [nodoc] boolean? supportsNotifyTag;
@@ -153,9 +164,6 @@ namespace fileSystemProvider {
     // or 0, then not limited.
     long? openedFilesLimit;
 
-    // Source of the file system data.
-    FileSystemSource? source;
-
     // Whether the file system supports the <code>tag</code> field for observed
     // directories. Required in order to enable the internal cache.
     [nodoc] boolean? supportsNotifyTag;