Pass const SharedBuffer to LocalFrame::ForceSynchronousDocumentInstall

This method shouldn't need to mutate the buffer. Clean up by adding some
local variables for the document and the associated parser while here.

Change-Id: Ic0f4541d557a07da833637906c01a1aa7dc37473
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2582220Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#835596}

third_party/blink/renderer/core/frame/local_frame.cc

@@ -2081,7 +2081,7 @@ bool LocalFrame::NeedsOcclusionTracking() const {
 
 void LocalFrame::ForceSynchronousDocumentInstall(
     const AtomicString& mime_type,
-    scoped_refptr<SharedBuffer> data) {
+    scoped_refptr<const SharedBuffer> data) {
   CHECK(GetDocument()->IsInitialEmptyDocument());
   DCHECK(!Client()->IsLocalFrameClientImpl());
 
@@ -2090,20 +2090,20 @@ void LocalFrame::ForceSynchronousDocumentInstall(
   GetDocument()->Shutdown();
   DomWindow()->ClearForReuse();
 
-  DomWindow()->InstallNewDocument(DocumentInit::Create()
-                                      .WithWindow(DomWindow(), nullptr)
-                                      .WithTypeFrom(mime_type));
-
-  GetDocument()->OpenForNavigation(kForceSynchronousParsing, mime_type,
-                                   AtomicString("UTF-8"));
+  Document* document =
+      DomWindow()->InstallNewDocument(DocumentInit::Create()
+                                          .WithWindow(DomWindow(), nullptr)
+                                          .WithTypeFrom(mime_type));
+  DocumentParser* parser = document->OpenForNavigation(
+      kForceSynchronousParsing, mime_type, AtomicString("UTF-8"));
   for (const auto& segment : *data)
-    GetDocument()->Parser()->AppendBytes(segment.data(), segment.size());
-  GetDocument()->Parser()->Finish();
+    parser->AppendBytes(segment.data(), segment.size());
+  parser->Finish();
 
   // Upon loading of SVGImages, log PageVisits in UseCounter.
   // Do not track PageVisits for inspector, web page popups, and validation
   // message overlays (the other callers of this method).
-  if (GetDocument()->IsSVGDocument())
+  if (document->IsSVGDocument())
     loader_.GetDocumentLoader()->GetUseCounterHelper().DidCommitLoad(this);
 }
 

third_party/blink/renderer/core/frame/local_frame.h

@@ -457,7 +457,7 @@ class CORE_EXPORT LocalFrame final
   // |mime_type| and populated with the contents of |data|. Only intended for
   // use in internal-implementation LocalFrames that aren't in the frame tree.
   void ForceSynchronousDocumentInstall(const AtomicString& mime_type,
-                                       scoped_refptr<SharedBuffer> data);
+                                       scoped_refptr<const SharedBuffer> data);
 
   bool should_send_resource_timing_info_to_parent() const {
     return should_send_resource_timing_info_to_parent_;