gdata: Support mounting archive files in GData cache.

chrome/browser/chromeos/gdata/gdata_file_system.h

Index: chrome/browser/chromeos/gdata/gdata_file_system.h
diff --git a/chrome/browser/chromeos/gdata/gdata_file_system.h b/chrome/browser/chromeos/gdata/gdata_file_system.h
index 97015aef1e580ae28d3a6c40e003a97727967fc9..da99ffb92dd1d8b7689954df68b9c00a8199c2a4 100644
--- a/chrome/browser/chromeos/gdata/gdata_file_system.h
+++ b/chrome/browser/chromeos/gdata/gdata_file_system.h
@@ -76,6 +76,11 @@ typedef base::Callback<void(base::PlatformFileError error,
                             GDataFileType file_type)>
     GetFileCallback;
 
+// Callback for SetMountedState.
+typedef base::Callback<void(base::PlatformFileError error,
+                            const FilePath& file_path)>
+    SetMountedStateCallback;
+
 // Used for file operations like removing files.
 typedef base::Callback<void(base::PlatformFileError error,
                             base::ListValue* feed_list)>
@@ -192,6 +197,7 @@ class GDataFileSystemInterface {
   enum CachedFileOrigin {
     CACHED_FILE_FROM_SERVER = 0,
     CACHED_FILE_LOCALLY_MODIFIED,
+    CACHED_FILE_MOUNTED,
   };
 
   // Enum defining type of file operation e.g. copy or move, etc.
@@ -365,6 +371,10 @@ class GDataFileSystemInterface {
   virtual bool GetFileInfoFromPath(const FilePath& gdata_file_path,
                                    GDataFileProperties* properties) = 0;
 
+  // Returns true if the given path is under gdata cache directory, i.e.
+  // <user_profile_dir>/GCache/v1
+  virtual bool IsUnderGDataCacheDirectory(const FilePath& path) const = 0;
+
   // Returns the tmp sub-directory under gdata cache directory, i.e.
   // <user_profile_dir>/GCache/v1/tmp
   virtual FilePath GetGDataCacheTmpDirectory() const = 0;
@@ -400,6 +410,12 @@ class GDataFileSystemInterface {
   virtual void SetPinState(const FilePath& file_path, bool to_pin,
                            const FileOperationCallback& callback) = 0;
 
+  // Marks or unmarks a file as locally mounted.
+  // When marked as mounted, the file is prevented from being modified
+  // or evicted from cache.
+  virtual void SetMountedState(const FilePath& file_path, bool to_mount,
+                               const SetMountedStateCallback& callback) = 0;
+
   // Creates a new file from |entry| under |virtual_dir_path|. Stored its
   // content from |file_content_path| into the cache.
   virtual void AddUploadedFile(const FilePath& virtual_dir_path,
@@ -466,6 +482,7 @@ class GDataFileSystem : public GDataFileSystemInterface,
                              const GetCacheStateCallback& callback) OVERRIDE;
   virtual bool GetFileInfoFromPath(const FilePath& gdata_file_path,
                                    GDataFileProperties* properties) OVERRIDE;
+  virtual bool IsUnderGDataCacheDirectory(const FilePath& path) const OVERRIDE;
   virtual FilePath GetGDataCacheTmpDirectory() const OVERRIDE;
   virtual FilePath GetGDataTempDownloadFolderPath() const OVERRIDE;
   virtual FilePath GetGDataTempDocumentFolderPath() const OVERRIDE;
@@ -481,6 +498,10 @@ class GDataFileSystem : public GDataFileSystemInterface,
   // Calls private Pin or Unpin methods with |callback|.
   virtual void SetPinState(const FilePath& file_path, bool pin,
                            const FileOperationCallback& callback) OVERRIDE;
+  virtual void SetMountedState(
+      const FilePath& file_path,
+      bool to_mount,
+      const SetMountedStateCallback& callback) OVERRIDE;
   virtual void AddUploadedFile(const FilePath& virtual_dir_path,
                                DocumentEntry* entry,
                                const FilePath& file_content_path,
@@ -1188,6 +1209,14 @@ class GDataFileSystem : public GDataFileSystemInterface,
                            FileOperationType file_operation_type,
                            base::PlatformFileError* error);
 
+  // Task posted from SetMountedState to modify cache state on the IO thread
+  // pool, which involves the following:
+  // - moves |source_path| to |dest_path|

[tbarzic, 2012/04/23 18:03:22]

what are |source_path| and |dest_path|?

[hshi, 2012/04/23 19:01:09]

In the case we're mounting, the |source_path| is the original (unmounted) path
to the cache blob, and |dest_path| is the mounted path; if we're unmounting it
is the opposite. 

Do you want me to put more explanation here? I'm just following the examples
such as the comments in UnpinOnIOThreadPool.

[hshi, 2012/04/23 20:45:47]

Done.

+  void SetMountedStateOnIOThreadPool(const FilePath& file_path,
+                                     bool to_mount,
+                                     base::PlatformFileError* error,
+                                     FilePath* cache_file_path);
+
   // Task posted from MarkDirtyInCache to modify cache state on the IO thread
   // pool, which involves the following:
   // - moves |source_path| to |dest_path| in persistent dir, where