Add granular file tracing.

base/files/file.cc

Index: base/files/file.cc
diff --git a/base/files/file.cc b/base/files/file.cc
index 4c0e5ded47c90d000a7fb6e80ff1e5a160445743..fde7e60321820d0546316ec077e54ce64bfbaa43 100644
--- a/base/files/file.cc
+++ b/base/files/file.cc
@@ -6,6 +6,8 @@
 #include "base/files/file_path.h"
 #include "base/metrics/histogram.h"
 #include "base/timer/elapsed_timer.h"
+#include "base/trace_event/scoped_file_trace.h"
+#include "base/trace_event/trace_event.h"
 
 #if defined(OS_POSIX)
 #include "base/files/file_posix_hooks_internal.h"
@@ -29,11 +31,11 @@ File::File()
 }
 
 #if !defined(OS_NACL)
-File::File(const FilePath& name, uint32 flags)
+File::File(const FilePath& path, uint32 flags)
     : error_details_(FILE_OK),
       created_(false),
       async_(false) {
-  Initialize(name, flags);
+  Initialize(path, flags);
 }
 #endif
 
@@ -57,18 +59,21 @@ File::File(Error error_details)
 
 File::File(RValue other)
     : file_(other.object->TakePlatformFile()),
+      path_(other.object->path_),
       error_details_(other.object->error_details()),
       created_(other.object->created()),
       async_(other.object->async_) {
 #if defined(OS_POSIX)
-   if (IsValid())
-     ProtectFileDescriptor(GetPlatformFile());
+  if (IsValid())
+    ProtectFileDescriptor(GetPlatformFile());
 #endif
 }
 
 File::~File() {
   // Go through the AssertIOAllowed logic.
   Close();
+  TRACE_EVENT_ASYNC_END1(ScopedFileTrace::kGroup, "File", this,
+                         "path", path_.AsUTF8Unsafe());
 }
 
 File& File::operator=(RValue other) {
@@ -83,12 +88,15 @@ File& File::operator=(RValue other) {
 }
 
 #if !defined(OS_NACL)
-void File::Initialize(const FilePath& name, uint32 flags) {
-  if (name.ReferencesParent()) {
+void File::Initialize(const FilePath& path, uint32 flags) {
+  path_ = path;
+  if (path_.ReferencesParent()) {
     error_details_ = FILE_ERROR_ACCESS_DENIED;
     return;
   }
-  DoInitialize(name, flags);
+  TRACE_EVENT_ASYNC_BEGIN1(ScopedFileTrace::kGroup, "File", this,
+                           "path", path_.AsUTF8Unsafe());

[Dan Beam, 2015/04/23 22:32:19]

this seemed like the sanest place to start this, but open to suggestions...

+  DoInitialize(flags);
 }
 #endif