Change SkTime::GetMSecs to double; ensure values stored in SkMSec do not overflow.

dm/DM.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "CrashHandler.h"
 #include "DMJsonWriter.h"
 #include "DMSrcSink.h"
@@ skipping 55 matching lines @@
         "this list, no image is written for that result.");
 
 DEFINE_int32(shards, 1, "We're splitting source data into this many shards.");
 DEFINE_int32(shard,  0, "Which shard do I run?");
 DEFINE_bool(simpleCodec, false, "Only decode images to native scale");
 
 using namespace DM;
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
-static const SkMSec kStartMs = SkTime::GetMSecs();
+static const double kStartMs = SkTime::GetMSecs();
 
 static FILE* gVLog;
 
 template <typename... Args>
 static void vlog(const char* fmt, Args&&... args) {
     if (gVLog) {
         fprintf(gVLog, "%s\t", HumanizeMs(SkTime::GetMSecs() - kStartMs).c_str());
         fprintf(gVLog, fmt, args...);
         fflush(gVLog);
     }
@@ skipping 1406 matching lines @@
                                                            Reporter* reporter,
                                                            GrContextFactory* factory);
 } // namespace skiatest
 
 #if !defined(SK_BUILD_FOR_IOS)
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
     return dm_main();
 }
 #endif