Add UMA histograms for the inter-process TimeTicks skew.

content/common/inter_process_time_ticks_converter.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.
 
 #ifndef CONTENT_COMMON_INTER_PROCESS_TIME_TICKS_CONVERTER_H_
 #define CONTENT_COMMON_INTER_PROCESS_TIME_TICKS_CONVERTER_H_
 
 #include "base/time/time.h"
 #include "content/common/content_export.h"
 
@@ skipping 43 matching lines @@
                                  const RemoteTimeTicks& remote_upper_bound);
 
   // Returns the value within the local's bounds that correlates to
   // |remote_ms|.
   LocalTimeTicks ToLocalTimeTicks(const RemoteTimeTicks& remote_ms) const;
 
   // Returns the equivalent delta after applying remote-to-local scaling to
   // |remote_delta|.
   LocalTimeDelta ToLocalTimeDelta(const RemoteTimeDelta& remote_delta) const;
 
+  // Returns true iff the TimeTicks are converted by adding a constant, without
+  // scaling. This is the case whenever the remote timespan is smaller than the
+  // local timespan, which should be the majority of cases due to IPC overhead.
+  bool IsSkewAdditiveForMetrics() const;
+
+  // Returns the (remote time) - (local time) difference estimated by the
+  // converter. This is the constant that is subtracted from remote TimeTicks to
+  // get local TimeTicks when no scaling is applied.
+  base::TimeDelta GetSkewForMetrics() const;
+
  private:
   int64 Convert(int64 value) const;
 
   // The local time which |remote_lower_bound_| is mapped to.
   int64 local_base_time_;
 
   int64 numerator_;
   int64 denominator_;
 
   int64 remote_lower_bound_;
@@ skipping 64 matching lines @@
   friend class InterProcessTimeTicksConverter;
 
   RemoteTimeTicks(int64 value) : value_(value) {}
 
   int64 value_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_INTER_PROCESS_TIME_TICKS_CONVERTER_H_