Make conversion between CPDF_Dest and its object explicit.

Precursor to taking a second shot at cleaning up the FPDF_*
APIs.  A FPDF_Dest is a CPDF_Array, and a CPDF_Dest
is a structure holding a FPDF_Dest.  This goes against the
convention that FPDF_ types get cast to CPDF_* types, so we
want to make it clear where objects are getting constructed,
etc.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/984703004

4 files changed, 28 insertions, 34 deletions

diff --git a/core/include/fpdfdoc/fpdf_doc.h b/core/include/fpdfdoc/fpdf_doc.h
index dbcc7f433e..dac215e711 100644
--- a/core/include/fpdfdoc/fpdf_doc.h
+++ b/core/include/fpdfdoc/fpdf_doc.h
@@ -124,28 +124,19 @@ public:
 class CPDF_Dest : public CFX_Object
 {
 public:
+    CPDF_Dest() : m_pObj(nullptr) { }
+    explicit CPDF_Dest(CPDF_Object* pObj) : m_pObj(pObj) { }
 
-    CPDF_Dest(CPDF_Object* pObj = NULL)
-    {
-        m_pObj = pObj;
-    }
-
-    operator CPDF_Object* () const
-    {
-        return m_pObj;
-    }
+    operator bool () const { return m_pObj != NULL; }
+    CPDF_Object* GetObject() const { return m_pObj; }
 
     CFX_ByteString		GetRemoteName();
-
     int					GetPageIndex(CPDF_Document* pDoc);
-
     FX_DWORD			GetPageObjNum();
-
     int					GetZoomMode();
-
     FX_FLOAT			GetParam(int index);
 
-
+protected:
     CPDF_Object*		m_pObj;
 };
 class CPDF_OCContext : public CFX_Object, public IPDF_OCContext
diff --git a/core/src/fpdfdoc/doc_action.cpp b/core/src/fpdfdoc/doc_action.cpp
index 324153563a..ac40335a4c 100644
--- a/core/src/fpdfdoc/doc_action.cpp
+++ b/core/src/fpdfdoc/doc_action.cpp
@@ -7,25 +7,26 @@
 #include "../../include/fpdfdoc/fpdf_doc.h"
 CPDF_Dest CPDF_Action::GetDest(CPDF_Document* pDoc) const
 {
-    if (m_pDict == NULL) {
-        return NULL;
+    if (!m_pDict) {
+        return CPDF_Dest();
     }
     CFX_ByteString type = m_pDict->GetString("S");
     if (type != "GoTo" && type != "GoToR") {
-        return NULL;
+        return CPDF_Dest();
     }
     CPDF_Object* pDest = m_pDict->GetElementValue("D");
-    if (pDest == NULL) {
-        return NULL;
+    if (!pDest) {
+        return CPDF_Dest();
     }
     if (pDest->GetType() == PDFOBJ_STRING || pDest->GetType() == PDFOBJ_NAME) {
         CPDF_NameTree name_tree(pDoc, FX_BSTRC("Dests"));
         CFX_ByteStringC name = pDest->GetString();
-        return name_tree.LookupNamedDest(pDoc, name);
-    } else if (pDest->GetType() == PDFOBJ_ARRAY) {
-        return (CPDF_Array*)pDest;
+        return CPDF_Dest(name_tree.LookupNamedDest(pDoc, name));
     }
-    return NULL;
+    if (pDest->GetType() == PDFOBJ_ARRAY) {
+        return CPDF_Dest((CPDF_Array*)pDest);
+    }
+    return CPDF_Dest();
 }
 const FX_CHAR* g_sATypes[] = {"Unknown", "GoTo", "GoToR", "GoToE", "Launch", "Thread", "URI", "Sound", "Movie",
                               "Hide",	"Named", "SubmitForm", "ResetForm", "ImportData", "JavaScript", "SetOCGState",
diff --git a/core/src/fpdfdoc/doc_bookmark.cpp b/core/src/fpdfdoc/doc_bookmark.cpp
index a3a194337e..9814de61bf 100644
--- a/core/src/fpdfdoc/doc_bookmark.cpp
+++ b/core/src/fpdfdoc/doc_bookmark.cpp
@@ -68,20 +68,21 @@ CFX_WideString CPDF_Bookmark::GetTitle() const
 CPDF_Dest CPDF_Bookmark::GetDest(CPDF_Document* pDocument) const
 {
     if (!m_pDict) {
-        return NULL;
+        return CPDF_Dest();
     }
     CPDF_Object* pDest = m_pDict->GetElementValue("Dest");
     if (!pDest) {
-        return NULL;
+        return CPDF_Dest();
     }
     if (pDest->GetType() == PDFOBJ_STRING || pDest->GetType() == PDFOBJ_NAME) {
         CPDF_NameTree name_tree(pDocument, FX_BSTRC("Dests"));
         CFX_ByteStringC name = pDest->GetString();
-        return name_tree.LookupNamedDest(pDocument, name);
-    } else if (pDest->GetType() == PDFOBJ_ARRAY) {
-        return (CPDF_Array*)pDest;
+        return CPDF_Dest(name_tree.LookupNamedDest(pDocument, name));
     }
-    return NULL;
+    if (pDest->GetType() == PDFOBJ_ARRAY) {
+        return CPDF_Dest((CPDF_Array*)pDest);
+    }
+    return CPDF_Dest();
 }
 CPDF_Action CPDF_Bookmark::GetAction() const
 {
diff --git a/core/src/fpdfdoc/doc_link.cpp b/core/src/fpdfdoc/doc_link.cpp
index e7b6be5ca4..b7c640af5e 100644
--- a/core/src/fpdfdoc/doc_link.cpp
+++ b/core/src/fpdfdoc/doc_link.cpp
@@ -90,16 +90,17 @@ CPDF_Dest CPDF_Link::GetDest(CPDF_Document* pDoc)
 {
     CPDF_Object* pDest = m_pDict->GetElementValue("Dest");
     if (pDest == NULL) {
-        return NULL;
+        return CPDF_Dest();
     }
     if (pDest->GetType() == PDFOBJ_STRING || pDest->GetType() == PDFOBJ_NAME) {
         CPDF_NameTree name_tree(pDoc, FX_BSTRC("Dests"));
         CFX_ByteStringC name = pDest->GetString();
-        return name_tree.LookupNamedDest(pDoc, name);
-    } else if (pDest->GetType() == PDFOBJ_ARRAY) {
-        return (CPDF_Array*)pDest;
+        return CPDF_Dest(name_tree.LookupNamedDest(pDoc, name));
     }
-    return NULL;
+    if (pDest->GetType() == PDFOBJ_ARRAY) {
+        return CPDF_Dest((CPDF_Array*)pDest);
+    }
+    return CPDF_Dest();
 }
 CPDF_Action CPDF_Link::GetAction()
 {