Differential updates for components.

chrome/browser/component_updater/component_patcher.h

Index: chrome/browser/component_updater/component_patcher.h
diff --git a/chrome/browser/component_updater/component_patcher.h b/chrome/browser/component_updater/component_patcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..70171154bfdde24668e281f783bc54c63899616a
--- /dev/null
+++ b/chrome/browser/component_updater/component_patcher.h
@@ -0,0 +1,63 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_PATCHER_H_
+#define CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_PATCHER_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "chrome/browser/component_updater/component_unpacker.h"
+
+namespace base {
+class FilePath;
+}
+
+class ComponentInstaller;
+
+// Applies a delta patch to a file. Specifically, creates a file at
+// |output_file| using |input_file| patched according to the algorithm
+// specified by |patch_type| using |patch_file|. Sets the value of error to
+// the error code of the failing patch operation, if there is such a failure.
+class ComponentPatcher {
+ public:
+  // The type of a patch file.
+  enum PatchType {
+    kPatchTypeUnknown,
+    kPatchTypeCourgette,
+    kPatchTypeBsdiff,
+  };
+
+  ComponentPatcher() {}
+  virtual ComponentUnpacker::Error Patch(PatchType patch_type,
+                                         const base::FilePath& input_file,
+                                         const base::FilePath& patch_file,
+                                         const base::FilePath& output_file,
+                                         int* error) = 0;
+  virtual ~ComponentPatcher() {}
+};
+
+class ComponentPatcherCrossPlatform : public ComponentPatcher {
+ public:
+  ComponentPatcherCrossPlatform();
+  virtual ComponentUnpacker::Error Patch(PatchType patch_type,
+                                         const base::FilePath& input_file,
+                                         const base::FilePath& patch_file,
+                                         const base::FilePath& output_file,
+                                         int* error) OVERRIDE;
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ComponentPatcherCrossPlatform);
+};
+
+// Recreates the content of a full CRX by taking the unpacked files of a
+// differential component update in |input_dir| and patching the installed
+// component files.
+// The resulting files are written into the |unpack_dir| directory.
+ComponentUnpacker::Error DifferentialUpdatePatch(
+    const base::FilePath& input_dir,
+    const base::FilePath& unpack_dir,
+    ComponentPatcher* component_patcher,
+    ComponentInstaller* installer,
+    int* error);
+
+#endif  // CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_PATCHER_H_