unsigned -> int for counts and indices in picture-related code

src/core/SkBigPicture.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 "SkBBoxHierarchy.h"
 #include "SkBigPicture.h"
 #include "SkPictureCommon.h"
@@ skipping 25 matching lines @@
     SkRecordDraw(*fRecord,
                  canvas,
                  this->drawablePicts(),
                  nullptr,
                  this->drawableCount(),
                  useBBH ? fBBH.get() : nullptr,
                  callback);
 }
 
 void SkBigPicture::partialPlayback(SkCanvas* canvas,
-                                   unsigned start,
-                                   unsigned stop,
+                                   int start,
+                                   int stop,
                                    const SkMatrix& initialCTM) const {
     SkASSERT(canvas);
     SkRecordPartialDraw(*fRecord,
                         canvas,
                         this->drawablePicts(),
                         this->drawableCount(),
                         start,
                         stop,
                         initialCTM);
 }
@@ skipping 21 matching lines @@
 SkPicture const* const* SkBigPicture::drawablePicts() const {
     return fDrawablePicts ? fDrawablePicts->begin() : nullptr;
 }
 
 SkBigPicture::Analysis::Analysis(const SkRecord& record) {
     SkTextHunter   text;
     SkBitmapHunter bitmap;
     SkPathCounter  path;
 
     bool hasText = false, hasBitmap = false;
-    for (unsigned i = 0; i < record.count(); i++) {
+    for (int i = 0; i < record.count(); i++) {
         hasText   = hasText   || record.visit<bool>(i,   text);
         hasBitmap = hasBitmap || record.visit<bool>(i, bitmap);
         record.visit<void>(i, path);
     }
 
     fHasText                    = hasText;
     fWillPlaybackBitmaps        = hasBitmap;
     fNumSlowPathsAndDashEffects = SkTMin<int>(path.fNumSlowPathsAndDashEffects, 255);
 }