Merge to XFA: Add type cast definitions for CPDF_String.

This Cl adds ToString, CPDF_Object::AsString and CPDF_Object::IsString and
updates the src to use them as needed.

BUG=pdfium:201
R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1417933002 .

(cherry picked from commit 53d3ab125ef583be8cfac907b308a6551b93067a)

Review URL: https://codereview.chromium.org/1408323006 .

2 files changed, 7 insertions, 8 deletions

diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
index 3f0de2d416..584f9c24d3 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
@@ -906,12 +906,13 @@ FX_BOOL CPDF_IndexedCS::v_Load(CPDF_Document* pDoc, CPDF_Array* pArray) {
     m_pCompMinMax[i * 2 + 1] -= m_pCompMinMax[i * 2];
   }
   m_MaxIndex = pArray->GetInteger(2);
+
   CPDF_Object* pTableObj = pArray->GetElementValue(3);
-  if (pTableObj == NULL) {
+  if (!pTableObj)
     return FALSE;
-  }
-  if (pTableObj->GetType() == PDFOBJ_STRING) {
-    m_Table = ((CPDF_String*)pTableObj)->GetString();
+
+  if (CPDF_String* pString = pTableObj->AsString()) {
+    m_Table = pString->GetString();
   } else if (pTableObj->GetType() == PDFOBJ_STREAM) {
     CPDF_StreamAcc acc;
     acc.LoadAllData((CPDF_Stream*)pTableObj, FALSE);
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index 1283a3a596..fbb364ee12 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -1359,10 +1359,8 @@ void CPDF_StreamContentParser::Handle_ShowText_Positioning() {
   }
   int n = pArray->GetCount(), nsegs = 0, i;
   for (i = 0; i < n; i++) {
-    CPDF_Object* pObj = pArray->GetElementValue(i);
-    if (pObj->GetType() == PDFOBJ_STRING) {
+    if (pArray->GetElementValue(i)->IsString())
       nsegs++;
-    }
   }
   if (nsegs == 0) {
     for (i = 0; i < n; i++) {
@@ -1379,7 +1377,7 @@ void CPDF_StreamContentParser::Handle_ShowText_Positioning() {
   FX_FLOAT fInitKerning = 0;
   for (i = 0; i < n; i++) {
     CPDF_Object* pObj = pArray->GetElementValue(i);
-    if (pObj->GetType() == PDFOBJ_STRING) {
+    if (pObj->IsString()) {
       CFX_ByteString str = pObj->GetString();
       if (str.IsEmpty()) {
         continue;