Add support for Flash Player Component updates on Linux

chrome/common/component_flash_hint_file.h

Index: chrome/common/component_flash_hint_file.h
diff --git a/chrome/common/component_flash_hint_file.h b/chrome/common/component_flash_hint_file.h
new file mode 100644
index 0000000000000000000000000000000000000000..c8c9e7768f59c23ce2e75dd5b976c723bcb6775f
--- /dev/null
+++ b/chrome/common/component_flash_hint_file.h
@@ -0,0 +1,61 @@
+// Copyright 2015 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_COMMON_COMPONENT_FLASH_HINT_FILE_H_
+#define CHROME_COMMON_COMPONENT_FLASH_HINT_FILE_H_
+
+#include <string>
+#include <vector>
+
+#include "base/files/file_util.h"
+#include "crypto/secure_hash.h"
+
+namespace chrome {
+
+// This class wraps the component updated flash hint file, which lives inside
+// the PepperFlash folder of  the user-data-dir, so that the Linux zygote
+// process can preload the right version of flash.
+class ComponentFlashHintFile {
+ public:
+  ComponentFlashHintFile();
+  // Records a new flash update into the hint file.
+  // unpacked_plugin is the current location of the plugin.
+  // moved_plugin is the location where the plugin will be loaded from.
+  bool RecordFlashUpdate(base::FilePath& unpacked_plugin,
+                         base::FilePath& moved_plugin,
+                         const std::string& version);
+  // Attempts to revert the flash hint file to its previous state, before this
+  // update.
+  bool Revert();
+  // Reports whether or not a hints file exists.
+  static bool DoesHintFileExist();
+  // Return the path of the component updated flash plugin, only if the file has
+  // the correct hash sum.
+  static bool VerifyAndReturnFlashLocation(base::FilePath* path,
+                                           std::string* version);
+
+ private:
+  // This will serialize the file to disk as JSON. The format is:
+  // {
+  //  "Version": 0x10,
+  //  "HashAlgorithm": SecureHash::SHA256,
+  //  "Hash": <Base64 Encoded Hash>,
+  //  "PluginPath": /path/to/component/updated/flash.so,
+  //  "PluginVersion": "1.0.0.1"
+  //  }
+  bool WriteToDisk(int version,
+                   crypto::SecureHash::Algorithm algorithm,
+                   const std::string& hash,
+                   base::FilePath& plugin_path,
+                   const std::string& flash_version);
+  // Indicates whether or not a hint file existed prior to this file being
+  // written.
+  bool was_previous_hint_file_;
+  // Contains the contents of the previous hint file.
+  std::string previous_hint_file_;
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_COMMON_COMPONENT_FLASH_HINT_FILE_H_