Clean up HTMLImportsController.cpp

- Remove an unused include
- Access root_ directly than via Root()

Bug: 
Change-Id: I2b9abe974dd7c3bcfc4921a1bd86833dc0b2efe4
Reviewed-on: https://chromium-review.googlesource.com/586212
Commit-Queue: Takeshi Yoshino <tyoshino@chromium.org>
Reviewed-by: Takayoshi Kochi <kochi@chromium.org>
Reviewed-by: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490972}

third_party/WebKit/Source/core/html/imports/HTMLImportsController.cpp

@@ -31,7 +31,6 @@
 #include "core/html/imports/HTMLImportsController.h"
 
 #include "core/dom/Document.h"
-#include "core/frame/LocalFrame.h"
 #include "core/frame/UseCounter.h"
 #include "core/html/imports/HTMLImportChild.h"
 #include "core/html/imports/HTMLImportChildClient.h"
@@ -76,7 +75,7 @@ HTMLImportChild* HTMLImportsController::CreateChild(
                                   ? HTMLImport::kSync
                                   : HTMLImport::kAsync;
   if (mode == HTMLImport::kAsync) {
-    UseCounter::Count(Root()->GetDocument(),
+    UseCounter::Count(root_->GetDocument(),
                       WebFeature::kHTMLImportsAsyncAttribute);
   }
 
@@ -84,7 +83,7 @@ HTMLImportChild* HTMLImportsController::CreateChild(
   child->SetClient(client);
   parent->AppendImport(child);
   loader->AddImport(child);
-  return Root()->Add(child);
+  return root_->Add(child);
 }
 
 HTMLImportChild* HTMLImportsController::Load(HTMLImport* parent,
@@ -94,10 +93,10 @@ HTMLImportChild* HTMLImportsController::Load(HTMLImport* parent,
 
   DCHECK(!url.IsEmpty());
   DCHECK(url.IsValid());
-  DCHECK(parent == Root() || ToHTMLImportChild(parent)->Loader()->IsFirstImport(
+  DCHECK(parent == root_ || ToHTMLImportChild(parent)->Loader()->IsFirstImport(
                                 ToHTMLImportChild(parent)));
 
-  if (HTMLImportChild* child_to_share_with = Root()->Find(url)) {
+  if (HTMLImportChild* child_to_share_with = root_->Find(url)) {
     HTMLImportLoader* loader = child_to_share_with->Loader();
     DCHECK(loader);
     HTMLImportChild* child = CreateChild(url, loader, parent, client);
@@ -123,7 +122,7 @@ HTMLImportChild* HTMLImportsController::Load(HTMLImport* parent,
 }
 
 Document* HTMLImportsController::Master() const {
-  return Root() ? Root()->GetDocument() : nullptr;
+  return root_ ? root_->GetDocument() : nullptr;
 }
 
 bool HTMLImportsController::ShouldBlockScriptExecution(
@@ -131,7 +130,7 @@ bool HTMLImportsController::ShouldBlockScriptExecution(
   DCHECK_EQ(document.ImportsController(), this);
   if (HTMLImportLoader* loader = LoaderFor(document))
     return loader->ShouldBlockScriptExecution();
-  return Root()->GetState().ShouldBlockScriptExecution();
+  return root_->GetState().ShouldBlockScriptExecution();
 }
 
 HTMLImportLoader* HTMLImportsController::CreateLoader() {