Make the PDF viewer background color a property of the instance.

pdf/instance.cc

Index: pdf/instance.cc
diff --git a/pdf/instance.cc b/pdf/instance.cc
index d34871725de6bfc8949adbe586cbb2a0438ba557..93daf6f163901ebb2ff18f0d69cd93442ebe14af 100644
--- a/pdf/instance.cc
+++ b/pdf/instance.cc
@@ -367,8 +367,6 @@ bool Instance::Init(uint32_t argc, const char* argn[], const char* argv[]) {
 
   CreatePageIndicator(IsPrintPreviewUrl(url));
 
-  engine_->SetBackgroundColor(kBackgroundColor);
-
   if (!full_) {
     // For PDFs embedded in a frame, we don't get the data automatically like we
     // do for full-frame loads.  Start loading the data manually.
@@ -2643,6 +2641,10 @@ bool Instance::IsPrintPreview() {
   return IsPrintPreviewUrl(url_);
 }
 
+uint32 Instance::GetBackgroundColor() {
+  return kBackgroundColor;
+}
+
 int Instance::GetPageNumberToDisplay() {
   int page = engine_->GetMostVisiblePage();
   if (IsPrintPreview() && !print_preview_page_numbers_.empty()) {