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 8030bf13734e8a6b20bfe4f8f45ccc738885e075..c848c3177bf458335d5cc72ab1cc3745b7d15578 100644
--- a/base/files/file.cc
+++ b/base/files/file.cc
@@ -6,6 +6,7 @@
 #include "base/files/file_path.h"
 #include "base/metrics/histogram.h"
 #include "base/timer/elapsed_timer.h"
+#include "base/trace_event/trace_event.h"
 
 namespace base {
 
@@ -22,14 +23,16 @@ File::File()
     : error_details_(FILE_ERROR_FAILED),
       created_(false),
       async_(false) {
+  TRACE_EVENT_ASYNC_BEGIN0(kTraceGroup, "File", this);
 }
 
 #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);
+  TRACE_EVENT_ASYNC_BEGIN0(kTraceGroup, "File", this);
+  Initialize(path, flags);
 }
 #endif
 
@@ -41,30 +44,36 @@ File::File(PlatformFile platform_file)
 #if defined(OS_POSIX)
   DCHECK_GE(platform_file, -1);
 #endif
+  TRACE_EVENT_ASYNC_BEGIN0(kTraceGroup, "File", this);
 }
 
 File::File(Error error_details)
     : error_details_(error_details),
       created_(false),
       async_(false) {
+  TRACE_EVENT_ASYNC_BEGIN0(kTraceGroup, "File", this);
 }
 
 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_) {
+  TRACE_EVENT_ASYNC_BEGIN0(kTraceGroup, "File", this);
 }
 
 File::~File() {
   // Go through the AssertIOAllowed logic.
   Close();
+  TRACE_EVENT_ASYNC_END0(kTraceGroup, "File", this);
 }
 
 File& File::operator=(RValue other) {
   if (this != other.object) {
     Close();
     SetPlatformFile(other.object->TakePlatformFile());
+    path_ = other.object->path_;
     error_details_ = other.object->error_details();
     created_ = other.object->created();
     async_ = other.object->async_;
@@ -73,12 +82,14 @@ 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_EVENT1(kTraceGroup, "Initialize", "path", path_.AsUTF8Unsafe());
+  DoInitialize(flags);
 }
 #endif
 
@@ -126,6 +137,9 @@ std::string File::ErrorToString(Error error) {
   return "";
 }
 
+// static
+const char File::kTraceGroup[] = TRACE_DISABLED_BY_DEFAULT("file");
+
 bool File::Flush() {
   ElapsedTimer timer;
   bool return_value = DoFlush();