Inject timestamps to resource messages.

content/common/resource_dispatcher.h

Index: content/common/resource_dispatcher.h
diff --git a/content/common/resource_dispatcher.h b/content/common/resource_dispatcher.h
index 141e89c188c4b102c01f4a61bdfbbdc6dd43c288..21c36902c845e716a34e6923926036abffbde251 100644
--- a/content/common/resource_dispatcher.h
+++ b/content/common/resource_dispatcher.h
@@ -71,6 +71,11 @@ class CONTENT_EXPORT ResourceDispatcher : public IPC::Listener {
     delegate_ = delegate;
   }
 
+  // Remembers IO thread timestamp for next resource message.
+  void set_io_timestamp(base::TimeTicks io_timestamp) {
+    io_timestamp_ = io_timestamp;
+  }
+
  private:
   friend class ResourceDispatcherTest;
 
@@ -157,6 +162,11 @@ class CONTENT_EXPORT ResourceDispatcher : public IPC::Listener {
       const PendingRequestInfo& request_info,
       const base::TimeTicks& browser_completion_time) const;
 
+  // Returns timestamp provided by IO thread. If no timestamp is supplied,
+  // then current time is returned. Saved timestamp is reset, so following
+  // invocations will return current time until set_io_timestamp is called.
+  base::TimeTicks ConsumeIOTimestamp();
+
   // Returns true if the message passed in is a resource related message.
   static bool IsResourceDispatcherMessage(const IPC::Message& message);
 
@@ -180,6 +190,9 @@ class CONTENT_EXPORT ResourceDispatcher : public IPC::Listener {
 
   ResourceDispatcherDelegate* delegate_;
 
+  // IO thread timestamp for ongoing IPC message.
+  base::TimeTicks io_timestamp_;
+
   DISALLOW_COPY_AND_ASSIGN(ResourceDispatcher);
 };