mediaview: Implement ArcDocumentsProviderBackendDelegate.

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

Index: chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h
diff --git a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h
index 123b268ed337951687eeabdd95f707f058a860ea..67b74cfbeaf84ddbaaa33eb7843fae83bf4cc84e 100644
--- a/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h
+++ b/chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root.h
@@ -16,6 +16,8 @@
 #include "components/arc/common/file_system.mojom.h"
 #include "storage/browser/fileapi/async_file_util.h"
 
+class GURL;
+
 namespace arc {
 
 class ArcDocumentsProviderDocument;
@@ -29,6 +31,8 @@ class ArcDocumentsProviderRoot {
  public:
   using GetFileInfoCallback = storage::AsyncFileUtil::GetFileInfoCallback;
   using ReadDirectoryCallback = storage::AsyncFileUtil::ReadDirectoryCallback;
+  using ResolveToContentUrlCallback =
+      base::Callback<void(const GURL& content_url)>;
 
   ArcDocumentsProviderRoot(const std::string& authority,
                            const std::string& root_document_id);
@@ -43,6 +47,12 @@ class ArcDocumentsProviderRoot {
   void ReadDirectory(const base::FilePath& path,
                      const ReadDirectoryCallback& callback);
 
+  // Resolves a file path into a content:// URL pointing to the file
+  // on DocumentsProvider. Returns URL that can be passed to
+  // ArcContentFileSystemFileSystemReader to read the content.
+  void ResolveToContentUrl(const base::FilePath& path,
+                           const ResolveToContentUrlCallback& callback);
+
  private:
   void GetFileInfoAfterCacheUpdate(const base::FilePath& path,
                                    const GetFileInfoCallback& callback);
@@ -56,6 +66,10 @@ class ArcDocumentsProviderRoot {
       const ReadDirectoryCallback& callback,
       base::Optional<std::vector<mojom::DocumentPtr>> children);
 
+  void ResolveToContentUrlAfterCacheUpdate(
+      const base::FilePath& path,
+      const ResolveToContentUrlCallback& callback);
+
   void UpdateDirectoryCacheUpTo(const base::FilePath& path,
                                 const base::Closure& callback);
   void UpdateDirectoryCacheIter(const base::FilePath& parent_directory_path,