SkPDF: Always give a default advance for glyphs.

gm/skbug_5321.cpp

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+
+// https://bugs.skia.org/5321
+// two strings should draw the same.  PDF did not.
+DEF_SIMPLE_GM(skbug_5321, canvas, 128, 128) {
+    SkPaint paint;
+    paint.setStyle(SkPaint::kFill_Style);
+    paint.setTextSize(30);
+    
+    paint.setTextEncoding(SkPaint::kUTF8_TextEncoding);
+    const char text[] = "x\314\200y";  // utf8(u"x\u0300y")
+    SkScalar x = 20, y = 45;
+    size_t byteLength = strlen(text);
+    canvas->drawText(text, byteLength, x, y, paint);
+    
+    int glyph_count = paint.countText(text, byteLength);
+    SkAutoTMalloc<SkScalar> widths(glyph_count);
+    (void)paint.getTextWidths(text, byteLength, &widths[0]);
+    for (int i = 0; i < glyph_count; ++i) {
+        SkScalar w = widths[i];
+        widths[i] = x;
+        x += w;
+    }
+    y += paint.getFontMetrics(nullptr);
+    canvas->drawPosTextH(text, byteLength, &widths[0], y, paint);
+}