Run V8 in predictable mode for pdfium_test

samples/pdfium_test.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include <list>
@@ skipping 564 matching lines @@
   std::list<std::string> files;
   if (!ParseCommandLine(args, &options, &files)) {
     fprintf(stderr, "%s", usage_string);
     return 1;
   }
 
   v8::V8::InitializeICU();
   v8::Platform* platform = v8::platform::CreateDefaultPlatform();
   v8::V8::InitializePlatform(platform);
   v8::V8::Initialize();
+  // By enabling predicatble mode, V8 won't post any background tasks.
+  const char predictable_flag[] = "--predictable";
+  v8::V8::SetFlagsFromString(predictable_flag, strlen(predictable_flag));
 
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
   v8::StartupData natives;
   v8::StartupData snapshot;
   if (!GetExternalData(options, "natives_blob.bin", &natives) ||
       !GetExternalData(options, "snapshot_blob.bin", &snapshot)) {
     return 1;
   }
   v8::V8::SetNativesDataBlob(&natives);
   v8::V8::SetSnapshotDataBlob(&snapshot);
@@ skipping 18 matching lines @@
     RenderPdf(filename, file_contents, file_length, options);
     free(file_contents);
   }
 
   FPDF_DestroyLibrary();
   v8::V8::ShutdownPlatform();
   delete platform;
 
   return 0;
 }