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

src/pdf/SkPDFMetadata.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPDFMetadata.h"
 #include "SkPDFTypes.h"
 #include <utility>
@@ skipping 37 matching lines @@
     return dict.release();
 }
 
 #ifdef SK_PDF_GENERATE_PDFA
 SkPDFMetadata::UUID SkPDFMetadata::uuid() const {
     // The main requirement is for the UUID to be unique; the exact
     // format of the data that will be hashed is not important.
     SkMD5 md5;
     const char uuidNamespace[] = "org.skia.pdf\n";
     md5.write(uuidNamespace, strlen(uuidNamespace));
-    SkMSec msec = SkTime::GetMSecs();
+    double msec = SkTime::GetMSecs();
     md5.write(&msec, sizeof(msec));
     SkTime::DateTime dateTime;
     SkTime::GetDateTime(&dateTime);
     md5.write(&dateTime, sizeof(dateTime));
     if (fCreation) {
         md5.write(fCreation.get(), sizeof(fCreation));
     }
     if (fModified) {
         md5.write(fModified.get(), sizeof(fModified));
     }
@@ skipping 273 matching lines @@
     SkString instanceID = uuid_to_string(instance);
     SkASSERT(0 == count_xml_escape_size(instanceID));
     return new PDFXMLObject(sk_string_printf(
             templateString, modificationDate.c_str(), creationDate.c_str(),
             metadataDate.c_str(), creator.c_str(), title.c_str(),
             subject.c_str(), author.c_str(), keywords1.c_str(),
             documentID.c_str(), instanceID.c_str(), keywords2.c_str()));
 }
 
 #endif  // SK_PDF_GENERATE_PDFA