[LayoutNG] Reference the canonical text in offset mapping

This patch adds a reference to the canonical text in offset mapping, so
that we don't need to make a detour to NGInlineNode when working on both
offset mapping and canonical text.

This patch is a preparation for adding NG version of
LayoutText::ContainsCaretOffset().

Bug: 771398
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: I8cf035c44ab90452819d92b91e7853b848781a41
Reviewed-on: https://chromium-review.googlesource.com/724286Reviewed-by: Emil A Eklund <eae@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509930}

third_party/WebKit/Source/core/layout/ng/inline/ng_inline_node.cc

@@ -405,6 +405,7 @@ const NGOffsetMappingResult& NGInlineNode::ComputeOffsetMappingIfNeeded() {
     // TODO(xiaochengh): This doesn't compute offset mapping correctly when
     // text-transform CSS property changes text length.
     NGOffsetMappingBuilder& mapping_builder = builder.GetOffsetMappingBuilder();
+    mapping_builder.SetDestinationString(Text());
     MutableData()->offset_mapping_ =
         WTF::MakeUnique<NGOffsetMappingResult>(mapping_builder.Build());
   }

third_party/WebKit/Source/core/layout/ng/inline/ng_inline_node_offset_mapping_test.cc

@@ -126,6 +126,8 @@ TEST_F(NGInlineNodeOffsetMappingTest, OneTextNode) {
   const Node* foo_node = layout_object_->GetNode();
   const NGOffsetMappingResult& result = GetOffsetMapping();
 
+  EXPECT_EQ("foo", result.GetText());
+
   ASSERT_EQ(1u, result.GetUnits().size());
   TEST_UNIT(result.GetUnits()[0], NGOffsetMappingUnitType::kIdentity, foo_node,
             0u, 3u, 0u, 3u);
@@ -173,6 +175,8 @@ TEST_F(NGInlineNodeOffsetMappingTest, TwoTextNodes) {
   const Node* bar_node = bar->GetNode();
   const NGOffsetMappingResult& result = GetOffsetMapping();
 
+  EXPECT_EQ("foobar", result.GetText());
+
   ASSERT_EQ(2u, result.GetUnits().size());
   TEST_UNIT(result.GetUnits()[0], NGOffsetMappingUnitType::kIdentity, foo_node,
             0u, 3u, 0u, 3u);
@@ -234,6 +238,8 @@ TEST_F(NGInlineNodeOffsetMappingTest, BRBetweenTextNodes) {
   const Node* bar_node = bar->GetNode();
   const NGOffsetMappingResult& result = GetOffsetMapping();
 
+  EXPECT_EQ("foo\nbar", result.GetText());
+
   ASSERT_EQ(3u, result.GetUnits().size());
   TEST_UNIT(result.GetUnits()[0], NGOffsetMappingUnitType::kIdentity, foo_node,
             0u, 3u, 0u, 3u);
@@ -271,6 +277,8 @@ TEST_F(NGInlineNodeOffsetMappingTest, OneTextNodeWithCollapsedSpace) {
   const Node* node = layout_object_->GetNode();
   const NGOffsetMappingResult& result = GetOffsetMapping();
 
+  EXPECT_EQ("foo bar", result.GetText());
+
   ASSERT_EQ(3u, result.GetUnits().size());
   TEST_UNIT(result.GetUnits()[0], NGOffsetMappingUnitType::kIdentity, node, 0u,
             4u, 0u, 4u);
@@ -346,6 +354,8 @@ TEST_F(NGInlineNodeOffsetMappingTest, FullyCollapsedWhiteSpaceNode) {
   const Node* space_node = space->GetNode();
   const NGOffsetMappingResult& result = GetOffsetMapping();
 
+  EXPECT_EQ("foo bar", result.GetText());
+
   ASSERT_EQ(3u, result.GetUnits().size());
   TEST_UNIT(result.GetUnits()[0], NGOffsetMappingUnitType::kIdentity, foo_node,
             0u, 4u, 0u, 4u);

third_party/WebKit/Source/core/layout/ng/inline/ng_offset_mapping_builder.cc

@@ -128,6 +128,13 @@ void NGOffsetMappingBuilder::Composite(const NGOffsetMappingBuilder& other) {
     mapping_[i] = other.mapping_[mapping_[i]];
 }
 
+void NGOffsetMappingBuilder::SetDestinationString(String string) {
+  // TODO(xiaochengh): Add the check below when we stop writing back to
+  // LayoutText for inline painting.
+  // DCHECK_EQ(mapping_.back(), string.length());
+  destination_string_ = string;
+}
+
 NGOffsetMappingResult NGOffsetMappingBuilder::Build() const {
   NGOffsetMappingResult::UnitVector units;
   NGOffsetMappingResult::RangeMap ranges;
@@ -171,7 +178,8 @@ NGOffsetMappingResult NGOffsetMappingBuilder::Build() const {
   if (current_node) {
     ranges.insert(current_node, std::make_pair(unit_range_start, units.size()));
   }
-  return NGOffsetMappingResult(std::move(units), std::move(ranges));
+  return NGOffsetMappingResult(std::move(units), std::move(ranges),
+                               destination_string_);
 }
 
 Vector<unsigned> NGOffsetMappingBuilder::DumpOffsetMappingForTesting() const {

third_party/WebKit/Source/core/layout/ng/inline/ng_offset_mapping_builder.h

@@ -8,6 +8,7 @@
 #include "core/CoreExport.h"
 #include "platform/wtf/Allocator.h"
 #include "platform/wtf/Vector.h"
+#include "platform/wtf/text/WTFString.h"
 
 namespace blink {
 
@@ -65,6 +66,9 @@ class CORE_EXPORT NGOffsetMappingBuilder {
   // Composite the offset mapping held by another builder to this builder.
   void Composite(const NGOffsetMappingBuilder&);
 
+  // Set the destination string of the offset mapping.
+  void SetDestinationString(String);
+
   // Finalize and return the offset mapping.
   NGOffsetMappingResult Build() const;
 
@@ -82,6 +86,9 @@ class CORE_EXPORT NGOffsetMappingBuilder {
   // the plain way. It will be replaced by a real implementation for efficiency.
   Vector<const LayoutText*> annotation_;
 
+  // The destination string of the offset mapping.
+  String destination_string_;
+
   DISALLOW_COPY_AND_ASSIGN(NGOffsetMappingBuilder);
 };
 

third_party/WebKit/Source/core/layout/ng/inline/ng_offset_mapping_result.cc

@@ -51,12 +51,14 @@ const NGOffsetMappingResult* GetNGOffsetMappingFor(const Node& node,
 }
 
 NGOffsetMappingResult::NGOffsetMappingResult(NGOffsetMappingResult&& other)
-    : NGOffsetMappingResult(std::move(other.units_), std::move(other.ranges_)) {
-}
+    : NGOffsetMappingResult(std::move(other.units_),
+                            std::move(other.ranges_),
+                            other.text_) {}
 
 NGOffsetMappingResult::NGOffsetMappingResult(UnitVector&& units,
-                                             RangeMap&& ranges)
-    : units_(units), ranges_(ranges) {}
+                                             RangeMap&& ranges,
+                                             String text)
+    : units_(units), ranges_(ranges), text_(text) {}
 
 NGOffsetMappingResult::~NGOffsetMappingResult() = default;
 

third_party/WebKit/Source/core/layout/ng/inline/ng_offset_mapping_result.h

@@ -10,6 +10,7 @@
 #include "platform/wtf/Allocator.h"
 #include "platform/wtf/HashMap.h"
 #include "platform/wtf/Vector.h"
+#include "platform/wtf/text/WTFString.h"
 
 namespace blink {
 
@@ -90,11 +91,12 @@ class CORE_EXPORT NGOffsetMappingResult {
       HashMap<Persistent<const Node>, std::pair<unsigned, unsigned>>;
 
   NGOffsetMappingResult(NGOffsetMappingResult&&);
-  NGOffsetMappingResult(UnitVector&&, RangeMap&&);
+  NGOffsetMappingResult(UnitVector&&, RangeMap&&, String);
   ~NGOffsetMappingResult();
 
   const UnitVector& GetUnits() const { return units_; }
   const RangeMap& GetRanges() const { return ranges_; }
+  const String& GetText() const { return text_; }
 
   // Returns the NGOffsetMappingUnit that contains the given offset in the DOM
   // node. If there are multiple qualifying units, returns the last one.
@@ -134,6 +136,7 @@ class CORE_EXPORT NGOffsetMappingResult {
  private:
   UnitVector units_;
   RangeMap ranges_;
+  String text_;
 
   DISALLOW_COPY_AND_ASSIGN(NGOffsetMappingResult);
 };