Use a monotonic clock (TimeTicks) to report network times to WebCore.

content/common/resource_messages.h

Index: content/common/resource_messages.h
diff --git a/content/common/resource_messages.h b/content/common/resource_messages.h
index cd748b8508231dd419cbdc8cdd15df04abf01e36..380085a04ae1fdb6f454a85e8582df3887ddb33f 100644
--- a/content/common/resource_messages.h
+++ b/content/common/resource_messages.h
@@ -147,7 +147,7 @@ IPC_MESSAGE_ROUTED4(ResourceMsg_RequestComplete,
                     int /* request_id */,
                     net::URLRequestStatus /* status */,
                     std::string /* security info */,
-                    base::Time /* completion_time */)
+                    base::TimeTicks /* completion_time */)

[darin (slow to review), 2011/08/29 23:42:56]

Are you sure it makes sense to send TimeTicks over IPC?  Do all processes really
have the same tick source?

[James Simonsen, 2011/08/30 00:09:31]

Yep. This has been a popular question in this code review. :)

All the platforms implement this with some sort of "system time" that's
implemented in the kernel and accessed with a system call. They all count time
since the OS booted.

Here are the some of my sources for each platform:

timeGetTime() - http://msdn.microsoft.com/en-us/library/dd743637(v=VS.85).aspx

clock_gettime() -
http://stackoverflow.com/questions/4943733/is-clock-monotonic-process-or-thre...

mach_absolute_time() -
http://google.com/codesearch#pFm0LxzAWvs/darwinsource/tarballs/apsl/xnu-792.t...

There is one discrepancy across platforms wrt suspending the machine. Mac and
Linux stop ticking while suspended. Windows continues to tick. We should
probably figure out how to normalize that across platforms, but it doesn't
actually interfere with anything here.

 
 // Resource messages sent from the renderer to the browser.