Revert "SkStream: remove some WStream functions from public api"

This reverts commit 8b681105077393ce8fb5bef0c1b55461ac2a5792.

Reason for revert: breaks bots

Original change's description:
> SkStream: remove some WStream functions from public api
> 
> move functions to SkStringPriv.h
> 
> also add SkStrAppendU32Hex() function, and re-write
> SkString::insertHex() to use SkStrAppendU32Hex.
> 
> add unit tests.
> 
> Change-Id: Ieda98fb4106db71565b607e593713a91a5ddd892
> Reviewed-on: https://skia-review.googlesource.com/151986
> Reviewed-by: Cary Clark <caryclark@google.com>
> Commit-Queue: Hal Canary <halcanary@google.com>

TBR=halcanary@google.com,bungeman@google.com,caryclark@google.com,reed@google.com

Change-Id: Idbac615092f46c18b38e08385dafba20930f0ff0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/152121
Reviewed-by: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
diff --git a/tools/skdiff/skdiff_html.cpp b/tools/skdiff/skdiff_html.cpp
index 11299c6..e0476bc 100644
--- a/tools/skdiff/skdiff_html.cpp
+++ b/tools/skdiff/skdiff_html.cpp
@@ -8,7 +8,6 @@
 #include "skdiff.h"
 #include "skdiff_html.h"
 #include "SkStream.h"
-#include "SkStreamPriv.h"
 #include "SkTime.h"
 
 /// Make layout more consistent by scaling image to 240 height, 360 width,
@@ -40,28 +39,28 @@
         SkTime::DateTime dt;
         SkTime::GetDateTime(&dt);
         stream->writeText("SkDiff run at ");
-        SkWStreamWriteDecAsText(stream, dt.fHour);
+        stream->writeDecAsText(dt.fHour);
         stream->writeText(":");
         if (dt.fMinute < 10) {
             stream->writeText("0");
         }
-        SkWStreamWriteDecAsText(stream, dt.fMinute);
+        stream->writeDecAsText(dt.fMinute);
         stream->writeText(":");
         if (dt.fSecond < 10) {
             stream->writeText("0");
         }
-        SkWStreamWriteDecAsText(stream, dt.fSecond);
+        stream->writeDecAsText(dt.fSecond);
         stream->writeText("<br>");
     }
-    SkWStreamWriteDecAsText(stream, matchCount);
+    stream->writeDecAsText(matchCount);
     stream->writeText(" of ");
-    SkWStreamWriteDecAsText(stream, differences.count());
+    stream->writeDecAsText(differences.count());
     stream->writeText(" diffs matched ");
     if (colorThreshold == 0) {
         stream->writeText("exactly");
     } else {
         stream->writeText("within ");
-        SkWStreamWriteDecAsText(stream, colorThreshold);
+        stream->writeDecAsText(colorThreshold);
         stream->writeText(" color units per component");
     }
     stream->writeText(".<br>");
@@ -79,12 +78,12 @@
 
 static void print_pixel_count(SkFILEWStream* stream, const DiffRecord& diff) {
     stream->writeText("<br>(");
-    SkWStreamWriteDecAsText(stream, static_cast<int>(diff.fFractionDifference *
+    stream->writeDecAsText(static_cast<int>(diff.fFractionDifference *
                                             diff.fBase.fBitmap.width() *
                                             diff.fBase.fBitmap.height()));
     stream->writeText(" pixels)");
 /*
-    SkWStreamWriteDecAsText(stream, diff.fWeightedFraction *
+    stream->writeDecAsText(diff.fWeightedFraction *
                            diff.fBaseWidth *
                            diff.fBaseHeight);
     stream->writeText(" weighted pixels)");
@@ -128,22 +127,22 @@
         stream->writeText("<br>");
         if (SkScalarRoundToInt(diff.fAverageMismatchA) > 0) {
           stream->writeText("<br>Average alpha channel mismatch ");
-          SkWStreamWriteDecAsText(stream, SkScalarRoundToInt(diff.fAverageMismatchA));
+          stream->writeDecAsText(SkScalarRoundToInt(diff.fAverageMismatchA));
         }
 
         stream->writeText("<br>Max alpha channel mismatch ");
-        SkWStreamWriteDecAsText(stream, SkScalarRoundToInt(diff.fMaxMismatchA));
+        stream->writeDecAsText(SkScalarRoundToInt(diff.fMaxMismatchA));
 
         stream->writeText("<br>Total alpha channel mismatch ");
-        SkWStreamWriteDecAsText(stream, static_cast<int>(diff.fTotalMismatchA));
+        stream->writeDecAsText(static_cast<int>(diff.fTotalMismatchA));
 
         stream->writeText("<br>");
         stream->writeText("<br>Average color mismatch ");
-        SkWStreamWriteDecAsText(stream, SkScalarRoundToInt(MAX3(diff.fAverageMismatchR,
+        stream->writeDecAsText(SkScalarRoundToInt(MAX3(diff.fAverageMismatchR,
                                                        diff.fAverageMismatchG,
                                                        diff.fAverageMismatchB)));
         stream->writeText("<br>Max color mismatch ");
-        SkWStreamWriteDecAsText(stream, MAX3(diff.fMaxMismatchR,
+        stream->writeDecAsText(MAX3(diff.fMaxMismatchR,
                                     diff.fMaxMismatchG,
                                     diff.fMaxMismatchB));
         stream->writeText("</td>");
@@ -167,7 +166,7 @@
     stream->writeText("\"><img src=\"");
     stream->writeText(path.c_str());
     stream->writeText("\" height=\"");
-    SkWStreamWriteDecAsText(stream, height);
+    stream->writeDecAsText(height);
     stream->writeText("px\"></a></td>");
 }