Integration and improvements of File API backends

1. More complete origin check in FileManagerThreadMsg
2. Add reference counting logic to file manage store and script API
3. Integrate the support of slicing

components/net_traits/blob_url_store.rs

@@ -2,37 +2,24 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use ipc_channel::ipc::IpcSender;
 use std::str::FromStr;
 use url::Url;
 use uuid::Uuid;
 
 /// Errors returns to BlobURLStoreMsg::Request
-#[derive(Clone, Serialize, Deserialize)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub enum BlobURLStoreError {
-    /// Invalid UUID key
-    InvalidKey,
+    /// Invalid File UUID
+    InvalidFileID,
     /// Invalid URL origin
     InvalidOrigin,
 }
 
-#[derive(Serialize, Deserialize)]
-pub enum BlobURLStoreMsg {
-    /// Add an entry and send back the associated uuid
-    /// XXX: Second field is an unicode-serialized Origin, it is a temporary workaround
-    ///      and should not be trusted. See issue https://github.com/servo/servo/issues/11722
-    AddEntry(BlobURLStoreEntry, String, IpcSender<Result<String, BlobURLStoreError>>),
-    /// Delete an entry by uuid
-    DeleteEntry(String),
-}
-
 /// Blob URL store entry, a packaged form of Blob DOM object
 #[derive(Clone, Serialize, Deserialize)]
 pub struct BlobURLStoreEntry {
     /// MIME type string
     pub type_string: String,
-    /// Some filename if the backend of Blob is a file
-    pub filename: Option<String>,
     /// Size of content in bytes
     pub size: u64,
     /// Content of blob