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

webkit/glue/resource_loader_bridge.h

 // Copyright (c) 2011 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.
 //
 // The intent of this file is to provide a type-neutral abstraction between
 // Chrome and WebKit for resource loading. This pure-virtual interface is
 // implemented by the embedder, which also provides a factory method Create
 // to instantiate this object.
 //
 // One of these objects will be created by WebKit for each request. WebKit
@@ skipping 34 matching lines @@
 // Structure containing timing information for the request. It addresses
 // http://groups.google.com/group/http-archive-specification/web/har-1-1-spec
 // and http://dev.w3.org/2006/webapi/WebTiming/ needs.
 //
 // All the values for starts and ends are given in milliseconds and are
 // offsets with respect to the given base time.
 struct ResourceLoadTimingInfo {
   ResourceLoadTimingInfo();
   ~ResourceLoadTimingInfo();
 
-  // All the values in this struct are given as offsets in milliseconds wrt
-  // this base time.
+  // All the values in this struct are given as offsets in ticks wrt
+  // this base tick count.

[wtc, 2011/08/26 23:39:15]

If the values are offsets wrt base_ticks, the values should
ideally have the type base::TimeDelta.  But it may be a
risky change to make quickly.

+  base::TimeTicks base_ticks;
+
+  // The value of Time::Now() when base_ticks was set.
   base::Time base_time;
 
   // The time that proxy processing started. For requests with no proxy phase,
   // this time is -1.
   int32 proxy_start;
 
   // The time that proxy processing ended. For reused sockets this time
   // is -1.
   int32 proxy_end;
 
@@ skipping 250 matching lines @@
     virtual void OnReceivedData(const char* data,
                                 int data_length,
                                 int encoded_data_length) = 0;
 
     // Called when metadata generated by the renderer is retrieved from the
     // cache. This method may be called zero or one times.
     virtual void OnReceivedCachedMetadata(const char* data, int len) { }
 
     // Called when the response is complete.  This method signals completion of
     // the resource load.ff
-    virtual void OnCompletedRequest(const net::URLRequestStatus& status,
-                                    const std::string& security_info,
-                                    const base::Time& completion_time) = 0;
+    virtual void OnCompletedRequest(
+        const net::URLRequestStatus& status,
+        const std::string& security_info,
+        const base::TimeTicks& completion_time) = 0;
   };
 
   // use Create() for construction, but anybody can delete at any time,
   // INCLUDING during processing of callbacks.
   virtual ~ResourceLoaderBridge();
 
   // Call this method to make a new instance.
   //
   // For HTTP(S) POST requests, the AppendDataToUpload and AppendFileToUpload
   // methods may be called to construct the body of the request.
@@ skipping 57 matching lines @@
   // construction must go through Create()
   ResourceLoaderBridge();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ResourceLoaderBridge);
 };
 
 }  // namespace webkit_glue
 
 #endif  // WEBKIT_GLUE_RESOURCE_LOADER_BRIDGE_H_