Fix the typo of "Resources" keyword

BUG=None
R=thestig@chromium.org

Review URL: https://codereview.chromium.org/420793004
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 1137007..b90c784 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -4181,7 +4181,7 @@
     if (!pParentDict) {
         return FALSE;
     }
-    CPDF_Object *pRet = pParentDict->GetElement("Resource");
+    CPDF_Object *pRet = pParentDict->GetElement("Resources");
     if (pRet) {
         m_pPageResource = pRet;
         return TRUE;
@@ -4287,11 +4287,12 @@
         }
     }
     if (m_pPageDict && !m_bNeedDownLoadResource) {
-        CPDF_Object *pRes = m_pPageDict->GetElement("Resource");
-        if (!pRes) {
+        m_pPageResource = m_pPageDict->GetElement("Resources");
+        if (!m_pPageResource) {
             m_bNeedDownLoadResource = HaveResourceAncestor(m_pPageDict);
+        } else {
+            m_bNeedDownLoadResource = TRUE;
         }
-        m_bNeedDownLoadResource = FALSE;
     }
     if (m_bNeedDownLoadResource) {
         FX_BOOL bRet = CheckResources(pHints);