Switch to using TimeTicks for profiling and histograms

Avoid using wall clock time, which can be changed by the user,
or impacted by Daylight Savings transitions etc.

BUG=14193
r=eroman
Review URL: http://codereview.chromium.org/1253005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@46821 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 6 insertions, 4 deletions

diff --git a/net/base/file_stream_posix.cc b/net/base/file_stream_posix.cc
index 65c8e2b..735f2b8 100644
--- a/net/base/file_stream_posix.cc
+++ b/net/base/file_stream_posix.cc
@@ -223,11 +223,12 @@ FileStream::AsyncContext::~AsyncContext() {
     // still running the IO task, or the completion callback is queued up on the
     // MessageLoopForIO, but AsyncContext() got deleted before then.
     const bool need_to_wait = !background_io_completed_.IsSignaled();
-    base::Time start = base::Time::Now();
+    base::TimeTicks start = base::TimeTicks::Now();
     RunAsynchronousCallback();
     if (need_to_wait) {
       // We want to see if we block the message loop for too long.
-      UMA_HISTOGRAM_TIMES("AsyncIO.FileStreamClose", base::Time::Now() - start);
+      UMA_HISTOGRAM_TIMES("AsyncIO.FileStreamClose",
+                          base::TimeTicks::Now() - start);
     }
   }
 }
diff --git a/net/base/file_stream_win.cc b/net/base/file_stream_win.cc
index 1ad9a34..6a6db90 100644
--- a/net/base/file_stream_win.cc
+++ b/net/base/file_stream_win.cc
@@ -74,14 +74,15 @@ class FileStream::AsyncContext : public MessageLoopForIO::IOHandler {
 FileStream::AsyncContext::~AsyncContext() {
   is_closing_ = true;
   bool waited = false;
-  base::Time start = base::Time::Now();
+  base::TimeTicks start = base::TimeTicks::Now();
   while (callback_) {
     waited = true;
     MessageLoopForIO::current()->WaitForIOCompletion(INFINITE, this);
   }
   if (waited) {
     // We want to see if we block the message loop for too long.
-    UMA_HISTOGRAM_TIMES("AsyncIO.FileStreamClose", base::Time::Now() - start);
+    UMA_HISTOGRAM_TIMES("AsyncIO.FileStreamClose",
+                        base::TimeTicks::Now() - start);
   }
 }