mediaview: Implement ArcDocumentsProviderBackendDelegate.

chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc

Index: chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
diff --git a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
index 87cd8b468a6bbee5625dbac532e12596cd8922d3..91443f6441e5e3fdba1acfeace607466a8bea476 100644
--- a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
+++ b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.cc
@@ -78,6 +78,22 @@ void ArcDocumentsProviderRoot::ReadDirectory(
                  weak_ptr_factory_.GetWeakPtr(), path, callback));
 }
 
+void ArcDocumentsProviderRoot::ResolveToContentUrl(
+    const base::FilePath& path,
+    const ResolveToContentUrlCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  // Skip a cache update if possible.
+  ArcDocumentsProviderDocument* entry = root_directory_->Lookup(path);
+  if (entry) {
+    ResolveToContentUrlAfterCacheUpdate(path, callback);
+    return;
+  }
+  UpdateDirectoryCacheUpTo(
+      path,
+      base::Bind(&ArcDocumentsProviderRoot::ResolveToContentUrlAfterCacheUpdate,
+                 weak_ptr_factory_.GetWeakPtr(), path, callback));
+}
+
 void ArcDocumentsProviderRoot::GetFileInfoAfterCacheUpdate(
     const base::FilePath& path,
     const GetFileInfoCallback& callback) {
@@ -157,6 +173,18 @@ void ArcDocumentsProviderRoot::ReadDirectoryWithChildDocuments(
   callback.Run(base::File::FILE_OK, entry_list, false /* has_more */);
 }
 
+void ArcDocumentsProviderRoot::ResolveToContentUrlAfterCacheUpdate(
+    const base::FilePath& path,
+    const ResolveToContentUrlCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  ArcDocumentsProviderDocument* entry = root_directory_->Lookup(path);
+  if (!entry) {
+    callback.Run(GURL());
+    return;
+  }
+  callback.Run(BuildDocumentUrl(authority_, entry->document_id()));
+}
+
 void ArcDocumentsProviderRoot::UpdateDirectoryCacheUpTo(
     const base::FilePath& path,
     const base::Closure& callback) {