Provide a method to remove inserted style sheet

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 40 matching lines @@
 #include "core/html/HTMLIFrameElement.h"
 #include "core/html/HTMLLinkElement.h"
 #include "core/html/HTMLSlotElement.h"
 #include "core/html/imports/HTMLImportsController.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/page/Page.h"
 #include "core/probe/CoreProbes.h"
 #include "core/svg/SVGStyleElement.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/instrumentation/tracing/TraceEvent.h"
+#include "platform/wtf/Atomics.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 StyleEngine::StyleEngine(Document& document)
     : document_(&document),
       is_master_(!document.ImportsController() ||
                  document.ImportsController()->Master() == &document),
       document_style_sheet_collection_(
@@ skipping 58 matching lines @@
       Master()->GetStyleEngine().UpdateActiveStyle();
   }
 
   if (tree_scope == document_)
     return GetDocumentStyleSheetCollection().StyleSheetsForStyleSheetList();
 
   return EnsureStyleSheetCollectionFor(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() {
   if (inspector_style_sheet_)
     return *inspector_style_sheet_;
 
   StyleSheetContents* contents =
       StyleSheetContents::Create(CSSParserContext::Create(*document_));
   inspector_style_sheet_ = CSSStyleSheet::Create(contents, *document_);
   MarkDocumentDirty();
@@ skipping 1015 matching lines @@
   visitor->Trace(media_query_evaluator_);
   visitor->Trace(style_invalidator_);
   visitor->Trace(font_selector_);
   visitor->Trace(text_to_sheet_cache_);
   visitor->Trace(sheet_to_text_cache_);
   visitor->Trace(tracker_);
   CSSFontSelectorClient::Trace(visitor);
 }
 
 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_);
 }
 
 }  // namespace blink