Provide a method to remove inserted style sheet

third_party/WebKit/Source/core/dom/StyleEngine.cpp

Index: third_party/WebKit/Source/core/dom/StyleEngine.cpp
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.cpp b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
index 0634c6ef6687e915f7a688860400b3aca78550f3..5eaca496d8c2fc955f8a86c1290a8b85dffc0f78 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.cpp
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
@@ -58,6 +58,7 @@
 #include "core/svg/SVGStyleElement.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/instrumentation/tracing/TraceEvent.h"
+#include "platform/wtf/Atomics.h"
 
 namespace blink {
 
@@ -136,10 +137,26 @@ StyleEngine::StyleSheetsForStyleSheetList(TreeScope& tree_scope) {
       ->StyleSheetsForStyleSheetList();
 }
 
-void StyleEngine::InjectAuthorSheet(StyleSheetContents* author_sheet) {
-  injected_author_style_sheets_.push_back(TraceWrapperMember<CSSStyleSheet>(
-      this, CSSStyleSheet::Create(author_sheet, *document_)));
+int StyleEngine::InjectAuthorSheet(StyleSheetContents* author_sheet) {
+  AtomicIncrement(&injected_author_sheets_id_count_);

[rune, 2017/05/16 09:00:58]

StyleEngine is not made to be thread-safe. Why not just pre-increment the
counter in the make_pair call?

[limasdf, 2017/05/18 12:32:53]

Done.

+  injected_author_style_sheets_.push_back(std::make_pair(
+      injected_author_sheets_id_count_,
+      TraceWrapperMember<CSSStyleSheet>(
+          this, CSSStyleSheet::Create(author_sheet, *document_))));
+
   MarkDocumentDirty();
+  return injected_author_sheets_id_count_;
+}
+
+bool StyleEngine::RemoveInjectedAuthorSheet(int id) {
+  for (size_t i = 0; i < injected_author_style_sheets_.size(); ++i) {

[rune, 2017/05/16 09:00:58]

I suppose we can assume the number of injected sheet is low enough to allow for
O(n) removal.

+    if (injected_author_style_sheets_[i].first == id) {
+      injected_author_style_sheets_.erase(i);
+      MarkDocumentDirty();
+      return true;
+    }
+  }
+  return false;
 }
 
 CSSStyleSheet& StyleEngine::EnsureInspectorStyleSheet() {
@@ -1175,8 +1192,8 @@ DEFINE_TRACE(StyleEngine) {
 }
 
 DEFINE_TRACE_WRAPPERS(StyleEngine) {
-  for (auto sheet : injected_author_style_sheets_) {
-    visitor->TraceWrappers(sheet);
+  for (const auto& sheet : injected_author_style_sheets_) {
+    visitor->TraceWrappers(sheet.second);
   }
   visitor->TraceWrappers(document_style_sheet_collection_);
 }