Switch CPU profile start/stop markers to monotonic time.

include/v8-profiler.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
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@@ skipping 100 matching lines @@
     */
   int GetSamplesCount() const;
 
   /**
     * Returns profile node corresponding to the top frame the sample at
     * the given index.
     */
   const CpuProfileNode* GetSample(int index) const;
 
   /**
-    * Returns time when the profile recording started (in microseconds
-    * since the Epoch).
+    * Returns time when the profile recording was started (in microseconds).

[yurys, 2014/04/18 12:43:30]

Please add a note about the time base.

[alph, 2014/04/18 13:19:58]

Done.

     */
   int64_t GetStartTime() const;
 
   /**
-    * Returns time when the profile recording was stopped (in microseconds
-    * since the Epoch).
+    * Returns time when the profile recording was stopped (in microseconds).
     */
   int64_t GetEndTime() const;
 
   /**
    * Deletes the profile and removes it from CpuProfiler's list.
    * All pointers to nodes previously returned become invalid.
    */
   void Delete();
 };
 
@@ skipping 477 matching lines @@
   uint32_t index;  // Index of the time interval that was changed.
   uint32_t count;  // New value of count field for the interval with this index.
   uint32_t size;  // New value of size field for the interval with this index.
 };
 
 
 }  // namespace v8
 
 
 #endif  // V8_V8_PROFILER_H_