Add granular file tracing.

base/files/file.h

 // Copyright (c) 2012 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 BASE_FILES_FILE_H_
 #define BASE_FILES_FILE_H_
 
 #include "build/build_config.h"
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #if defined(OS_POSIX)
 #include <sys/stat.h>
 #endif
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
+#include "base/files/file_path.h"
+#include "base/files/file_tracing.h"
 #include "base/files/scoped_file.h"
 #include "base/gtest_prod_util.h"
 #include "base/move.h"
 #include "base/time/time.h"
 
 #if defined(OS_WIN)
 #include "base/win/scoped_handle.h"
 #endif
 
 FORWARD_DECLARE_TEST(FileTest, MemoryCorruption);
 
 namespace base {
 
-class FilePath;
-
 #if defined(OS_WIN)
 typedef HANDLE PlatformFile;
 #elif defined(OS_POSIX)
 typedef int PlatformFile;
 
 #if defined(OS_BSD) || defined(OS_MACOSX) || defined(OS_NACL)
 typedef struct stat stat_wrapper_t;
 #else
 typedef struct stat64 stat_wrapper_t;
 #endif
@@ skipping 109 matching lines @@
     // The last accessed time of a file.
     Time last_accessed;
 
     // The creation time of a file.
     Time creation_time;
   };
 
   File();
 
   // Creates or opens the given file. This will fail with 'access denied' if the
-  // |name| contains path traversal ('..') components.
-  File(const FilePath& name, uint32 flags);
+  // |path| contains path traversal ('..') components.
+  File(const FilePath& path, uint32 flags);
 
   // Takes ownership of |platform_file|.
   explicit File(PlatformFile platform_file);
 
   // Creates an object with a specific error_details code.
   explicit File(Error error_details);
 
   // Move constructor for C++03 move emulation of this type.
   File(RValue other);
 
   ~File();
 
   // Move operator= for C++03 move emulation of this type.
   File& operator=(RValue other);
 
   // Creates or opens the given file.
-  void Initialize(const FilePath& name, uint32 flags);
+  void Initialize(const FilePath& path, uint32 flags);
 
   bool IsValid() const;
 
   // Returns true if a new file was created (or an old one truncated to zero
   // length to simulate a new file, which can happen with
   // FLAG_CREATE_ALWAYS), and false otherwise.
   bool created() const { return created_; }
 
   // Returns the OS result of opening this file. Note that the way to verify
   // the success of the operation is to use IsValid(), not this method:
-  //   File file(name, flags);
+  //   File file(path, flags);
   //   if (!file.IsValid())
   //     return;
   Error error_details() const { return error_details_; }
 
   PlatformFile GetPlatformFile() const;
   PlatformFile TakePlatformFile();
 
   // Destroying this object closes the file automatically.
   void Close();
 
@@ skipping 93 matching lines @@
 #elif defined(OS_POSIX)
   static Error OSErrorToFileError(int saved_errno);
 #endif
 
   // Converts an error value to a human-readable form. Used for logging.
   static std::string ErrorToString(Error error);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(::FileTest, MemoryCorruption);
 
+  friend class FileTracing::ScopedTrace;
+
 #if defined(OS_POSIX)
   // Encloses a single ScopedFD, saving a cheap tamper resistent memory checksum
   // alongside it. This checksum is validated at every access, allowing early
   // detection of memory corruption.
 
   // TODO(gavinp): This is in place temporarily to help us debug
   // https://crbug.com/424562 , which can't be reproduced in valgrind. Remove
   // this code after we have fixed this issue.
   class MemoryCheckingScopedFD {
    public:
@@ skipping 25 matching lines @@
     // failing a CHECK if they do not.
     void Check() const;
 
     void UpdateChecksum();
 
     ScopedFD file_;
     unsigned int file_memory_checksum_;
   };
 #endif
 
-  // Creates or opens the given file. Only called if |name| has no traversal
-  // ('..') components.
-  void DoInitialize(const FilePath& name, uint32 flags);
+  // Creates or opens the given file. Only called if |path_| has no
+  // traversal ('..') components.
+  void DoInitialize(uint32 flags);
 
   // TODO(tnagel): Reintegrate into Flush() once histogram isn't needed anymore,
   // cf. issue 473337.
   bool DoFlush();
 
   void SetPlatformFile(PlatformFile file);
 
 #if defined(OS_WIN)
   win::ScopedHandle file_;
 #elif defined(OS_POSIX)
   MemoryCheckingScopedFD file_;
 #endif
 
+  // Path that |Initialize()| was called with. Only set if safe (i.e. no '..').
+  FilePath path_;
+
+  // Object tied to the lifetime of |this| that enables/disables tracing.
+  FileTracing::ScopedEnabler trace_enabler_;
+
   Error error_details_;
   bool created_;
   bool async_;
 };
 
 }  // namespace base
 
 #endif  // BASE_FILES_FILE_H_