pdfviewer: fix warning in release

experimental/PdfViewer/pdfparser/native/SkNativeParsedPDF.cpp

 #include "SkNativeParsedPDF.h"
 #include "SkPdfNativeTokenizer.h"
 #include "SkPdfBasics.h"
 #include "SkPdfObject.h"
 
 #include <stdio.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 
@@ skipping 57 matching lines @@
 // 2) recoverable corupt file: remove endobj, endsteam, remove other keywords, use other white spaces, insert comments randomly, ...
 // 3) irrecoverable corrupt file
 SkNativeParsedPDF::SkNativeParsedPDF(const char* path)
         : fAllocator(new SkPdfAllocator())
         , fRootCatalogRef(NULL)
         , fRootCatalog(NULL) {
     gDoc = this;
     FILE* file = fopen(path, "r");
     fContentLength = getFileSize(path);
     fFileContent = new unsigned char[fContentLength + 1];
-    fread(fFileContent, fContentLength, 1, file);
+    bool ok = (0 != fread(fFileContent, fContentLength, 1, file));
     fFileContent[fContentLength] = '\0';
     fclose(file);
     file = NULL;
 
+    if (!ok) {
+        // TODO(edisonn): report read error
+        return;  // Doc will have 0 pages
+    }
+
     unsigned char* eofLine = lineHome(fFileContent, fFileContent + fContentLength - 1);
     unsigned char* xrefByteOffsetLine = previousLineHome(fFileContent, eofLine);
     unsigned char* xrefstartKeywordLine = previousLineHome(fFileContent, xrefByteOffsetLine);
 
     if (strcmp((char*)xrefstartKeywordLine, "startxref") != 0) {
         // TODO(edisonn): report/issue
     }
 
     long xrefByteOffset = atol((const char*)xrefByteOffsetLine);
 
@@ skipping 324 matching lines @@
     return (SkPdfObject*)ref;
 }
 
 size_t SkNativeParsedPDF::bytesUsed() const {
     return fAllocator->bytesUsed() +
            fContentLength +
            fObjects.count() * sizeof(PublicObjectEntry) +
            fPages.count() * sizeof(SkPdfPageObjectDictionary*) +
            sizeof(*this);
 }