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

samplecode/SampleClipDrawMatch.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 "SampleCode.h"
 #include "SkCanvas.h"
 #include "SkInterpolator.h"
@@ skipping 103 matching lines @@
     } 
 }
 
 class ClipDrawMatchView : public SampleView {
 public:
     ClipDrawMatchView() : fTrans(2, 5), fGeom(kRect_Geometry), fClipFirst(true), fSign(1) {
         SkScalar values[2];
 
         fTrans.setRepeatCount(999);
         values[0] = values[1] = 0;
-        fTrans.setKeyFrame(0, SkTime::GetMSecs() + 1000, values);
+        fTrans.setKeyFrame(0, GetMSecs() + 1000, values);
         values[1] = 1;
-        fTrans.setKeyFrame(1, SkTime::GetMSecs() + 2000, values);
+        fTrans.setKeyFrame(1, GetMSecs() + 2000, values);
         values[0] = values[1] = 1;
-        fTrans.setKeyFrame(2, SkTime::GetMSecs() + 3000, values);
+        fTrans.setKeyFrame(2, GetMSecs() + 3000, values);
         values[1] = 0;
-        fTrans.setKeyFrame(3, SkTime::GetMSecs() + 4000, values);
+        fTrans.setKeyFrame(3, GetMSecs() + 4000, values);
         values[0] = 0;
-        fTrans.setKeyFrame(4, SkTime::GetMSecs() + 5000, values);
+        fTrans.setKeyFrame(4, GetMSecs() + 5000, values);
     }
 
 protected:
     bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "ClipDrawMatch");
             return true;
         }
         SkUnichar uni;
         if (SampleCode::CharQ(*evt, &uni)) {
@@ skipping 81 matching lines @@
 
         draw_normal_geom(canvas, offset, fGeom, useAA);
 
         if (!fClipFirst) {
             this->drawClippedGeom(canvas, offset, useAA);
         }
     }
 
     void onDrawContent(SkCanvas* canvas) override {
         SkScalar trans[2];
-        fTrans.timeToValues(SkTime::GetMSecs(), trans);
+        fTrans.timeToValues(GetMSecs(), trans);
 
         SkPoint offset;
         offset.set(trans[0], trans[1]);
 
         int saveCount = canvas->save();
         this->drawGeometry(canvas, offset, false);
         canvas->restoreToCount(saveCount);
 
         this->inval(nullptr);
     }
 
+    SkMSec GetMSecs() const {
+        return static_cast<SkMSec>(SkTime::GetMSecs() - fStart);
+    }
+
 private:
     SkInterpolator  fTrans;
     Geometry        fGeom;
     bool            fClipFirst;
     int             fSign;
+    const double    fStart = SkTime::GetMSecs();
 
     typedef SampleView INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static SkView* MyFactory() { return new ClipDrawMatchView; }
 static SkViewRegister reg(MyFactory);