[LayoutNG] Misc fixes in ShapingLineBreaker

third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.h

Index: third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.h
diff --git a/third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.h b/third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.h
index b6923ef937d9907360a26a68e6d34b09bb4c0b3f..8ce29a181949413d690beee62a5f48f4de2505e7 100644
--- a/third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.h
+++ b/third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.h
@@ -67,6 +67,8 @@ class PLATFORM_EXPORT ShapeResult : public RefCounted<ShapeResult> {
   float Width() const { return width_; }
   LayoutUnit SnappedWidth() const { return LayoutUnit::FromFloatCeil(width_); }
   const FloatRect& Bounds() const { return glyph_bounding_box_; }
+  // The character start index of a range shape result.
+  unsigned CharacterStartIndex() const;

[eae, 2017/05/12 18:45:49]

CharacterOffset perhaps and CharacterLength for (NumCharacters) to be more
consistent?

or CharacterStartIndex and CharacterEndIndex

[kojii, 2017/05/12 19:08:13]

Existing functions such as OffsetForPosition() use "Offset" meaning offset from
the first shape range, so I avoided "Offset". ...or should all these function
changed to use offset from the beginning of a full string?

If not, I might add CharacterEndIndex(). Or if you get better suggestions after
reading my reply.

[eae, 2017/05/12 21:24:05]

Ah, fair enough. Perhaps we could be even more explicit and call it
StartIndexForResult and EndIndexForResult?

Either way, as long as the comment is accurate (which it is) the name is fine as
is. Thanks for the explanation.

   unsigned NumCharacters() const { return num_characters_; }
   void FallbackFonts(HashSet<const SimpleFontData*>*) const;
   TextDirection Direction() const {
@@ -78,6 +80,14 @@ class PLATFORM_EXPORT ShapeResult : public RefCounted<ShapeResult> {
   // For memory reporting.
   size_t ByteSize() const;
 
+  enum OffsetOptions {
+    // If the position is outside of this result, returns the start or the end
+    // offset depends on the position.
+    kOutsideAsStartOrEnd,
+    // If the position is outside of this result, returns the most right offset.
+    kOutsideAsRight,
+  };
+  unsigned OffsetForPosition(float target_x, OffsetOptions) const;

[eae, 2017/05/12 18:45:49]

Isn't kOutsideAsStartOrEnd always the desirable behavior?

[kojii, 2017/05/12 19:08:13]

I think so, but there are bunch of existing callers and hard to determine if
anyone is relying on kOutsideAsRight behavior.

I'll try to change and see if any tests break.

   unsigned OffsetForPosition(float target_x, bool include_partial_glyphs) const;
   float PositionForOffset(unsigned offset) const;
   LayoutUnit SnappedStartPositionForOffset(unsigned offset) const {