Add private PPAPI interfaces for PDFium accessibility.

ppapi/thunk/ppb_pdf_api.h

Index: ppapi/thunk/ppb_pdf_api.h
diff --git a/ppapi/thunk/ppb_pdf_api.h b/ppapi/thunk/ppb_pdf_api.h
index 928c8cdc9fe0966c63b4280d4b5e9667f58987c3..13eca9fef1d51a3d23f4d9e98896b647e9684acf 100644
--- a/ppapi/thunk/ppb_pdf_api.h
+++ b/ppapi/thunk/ppb_pdf_api.h
@@ -32,7 +32,18 @@ class PPB_PDF_API {
                                          int* natives_size_out,
                                          const char** snapshot_data_out,
                                          int* snapshot_size_out) = 0;
-
+  virtual void SetAccessibilityViewportInfo(
+      PP_PrivateAccessibilityViewportInfo* viewport_info) = 0;
+  virtual void SetAccessibilityDocInfo(PP_PrivateAccessibilityDocInfo* doc_info)
+      = 0;
+  virtual void SetAccessibilityPageInfo(
+      uint32_t page_index,
+      PP_PrivateAccessibilityPageInfo* page_info) = 0;
+  virtual void SetAccessibilityTextRunInfo(
+      uint32_t page_index,
+      uint32_t text_run_index,
+      PP_PrivateAccessibilityTextRunInfo* text_run_info,
+      PP_PrivateAccessibilityCharInfo chars[]) = 0;
   static const SingletonResourceID kSingletonResourceID = PDF_SINGLETON_ID;
 };