Fix file reading success checking in image_sanitizer.cc

Bug: None
Change-Id: I6930083dabdb2596f8760737c8d9d474d41c2d27
Reviewed-on: https://chromium-review.googlesource.com/965621Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Istiaque Ahmed <lazyboy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544261}

extensions/browser/image_sanitizer.cc

@@ -29,8 +29,9 @@ std::tuple<std::vector<uint8_t>, bool, bool> ReadAndDeleteBinaryFile(
   int64_t file_size;
   if (base::GetFileSize(path, &file_size)) {
     contents.resize(file_size);
-    read_success = base::ReadFile(
-        path, reinterpret_cast<char*>(contents.data()), file_size);
+    read_success =
+        base::ReadFile(path, reinterpret_cast<char*>(contents.data()),
+                       file_size) == file_size;
   }
   bool delete_success = base::DeleteFile(path, /*recursive=*/false);
   return std::make_tuple(std::move(contents), read_success, delete_success);