Use a counter for DocumentLoader::BlockParser().

Replace usage of a bool by a counter to control whether or not the
parser is allowed to read new data or not.

Since WebDocumentLoader::BlockParser() is public, they may be several
components trying to pause the parser at the same time. Using a counter
make it possible to wait for all of them to call
WebDocumentLoader::ResumeParser().

This is a follow up for:
https://chromium-review.googlesource.com/982059

Bug: 822650
Change-Id: Id6d42f911f4b6e69ca942d8bf19acd296327d419
Reviewed-on: https://chromium-review.googlesource.com/992033Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548028}

third_party/WebKit/Source/core/loader/DocumentLoader.cpp

@@ -473,7 +473,7 @@ void DocumentLoader::FinishedLoading(TimeTicks finish_time) {
 
   application_cache_host_->FinishedLoadingMainResource();
   if (parser_) {
-    if (is_parser_blocked_) {
+    if (parser_blocked_count_) {
       finished_loading_ = true;
     } else {
       parser_->Finish();
@@ -727,7 +727,7 @@ void DocumentLoader::CommitData(const char* bytes, size_t length) {
   if (length)
     data_received_ = true;
 
-  if (is_parser_blocked_) {
+  if (parser_blocked_count_) {
     if (!committed_data_buffer_)
       committed_data_buffer_ = SharedBuffer::Create();
     committed_data_buffer_->Append(bytes, length);
@@ -1152,13 +1152,15 @@ void DocumentLoader::ReplaceDocumentWhileExecutingJavaScriptURL(
 }
 
 void DocumentLoader::BlockParser() {
-  DCHECK(!is_parser_blocked_);
-  is_parser_blocked_ = true;
+  parser_blocked_count_++;
 }
 
 void DocumentLoader::ResumeParser() {
-  DCHECK(is_parser_blocked_);
-  is_parser_blocked_ = false;
+  parser_blocked_count_--;
+  DCHECK_GE(parser_blocked_count_, 0);
+
+  if (parser_blocked_count_ != 0)
+    return;
 
   if (committed_data_buffer_ && !committed_data_buffer_->IsEmpty()) {
     // Don't recursively process data.

third_party/WebKit/Source/core/loader/DocumentLoader.h

@@ -244,7 +244,9 @@ class CORE_EXPORT DocumentLoader
     return devtools_navigation_token_;
   }
 
-  // Can be used to block the parser.
+  // Can be used to temporarily suspend feeding the parser with new data. The
+  // parser will be allowed to read new data when ResumeParser() is called the
+  // same number of time than BlockParser().
   void BlockParser();
   void ResumeParser();
 
@@ -387,7 +389,7 @@ class CORE_EXPORT DocumentLoader
   State state_;
 
   // Used to block the parser.
-  bool is_parser_blocked_ = false;
+  int parser_blocked_count_ = 0;
   bool finished_loading_ = false;
   scoped_refptr<SharedBuffer> committed_data_buffer_;
 

third_party/WebKit/public/web/WebDocumentLoader.h

@@ -148,8 +148,9 @@ class BLINK_EXPORT WebDocumentLoader {
 
   virtual bool GetIsAdSubframe() const = 0;
 
-  // Used to pause or resume the parser. The document loader is still allowed to
-  // fetch new data.
+  // Can be used to temporarily suspend feeding the parser with new data. The
+  // parser will be allowed to read new data when ResumeParser() is called the
+  // same number of time than BlockParser().
   virtual void BlockParser() = 0;
   virtual void ResumeParser() = 0;