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

pdf/instance.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PDF_INSTANCE_H_
 #define PDF_INSTANCE_H_
 
 #include <queue>
 #include <set>
 #include <string>
@@ skipping 156 matching lines @@
                     bool case_sensitive,
                     std::vector<SearchStringResult>* results) override;
   void DocumentPaintOccurred() override;
   void DocumentLoadComplete(int page_count) override;
   void DocumentLoadFailed() override;
   pp::Instance* GetPluginInstance() override;
   void DocumentHasUnsupportedFeature(const std::string& feature) override;
   void DocumentLoadProgress(uint32 available, uint32 doc_size) override;
   void FormTextFieldFocusChange(bool in_focus) override;
   bool IsPrintPreview() override;
+  uint32 GetBackgroundColor() override;
 
   // ControlOwner implementation.
   void OnEvent(uint32 control_id, uint32 event_id, void* data) override;
   void Invalidate(uint32 control_id, const pp::Rect& rc) override;
   uint32 ScheduleTimer(uint32 control_id, uint32 timeout_ms) override;
   void SetEventCapture(uint32 control_id, bool set_capture) override;
   void SetCursor(uint32 control_id, PP_CursorType_Dev cursor_type) override;
   pp::Instance* GetInstance() override;
 
   bool dont_paint() const { return dont_paint_; }
@@ skipping 342 matching lines @@
                        const std::vector<pp::Var>& args,
                        pp::Var* exception);
 
  private:
   Instance* instance_;
 };
 
 }  // namespace chrome_pdf
 
 #endif  // PDF_INSTANCE_H_