Make sure all variables in PerformanceResourceTiming are initialized

Bug: 967996
Change-Id: Ia672a9a80d01ca061585dc8c1cd9f2632b8d0788
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635670Reviewed-by: Nicolás Peña Moreno <npm@chromium.org>
Commit-Queue: Yoav Weiss <yoavweiss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664332}

third_party/blink/renderer/core/timing/performance_resource_timing.h

@@ -113,13 +113,13 @@ class CORE_EXPORT PerformanceResourceTiming : public PerformanceEntry {
   scoped_refptr<ResourceLoadTiming> timing_;
   TimeTicks last_redirect_end_time_;
   TimeTicks response_end_;
-  uint64_t transfer_size_;
-  uint64_t encoded_body_size_;
-  uint64_t decoded_body_size_;
-  bool did_reuse_connection_;
-  bool allow_timing_details_;
-  bool allow_redirect_details_;
-  bool allow_negative_value_;
+  uint64_t transfer_size_ = 0;
+  uint64_t encoded_body_size_ = 0;
+  uint64_t decoded_body_size_ = 0;
+  bool did_reuse_connection_ = false;
+  bool allow_timing_details_ = false;
+  bool allow_redirect_details_ = false;
+  bool allow_negative_value_ = false;
   bool is_secure_context_ = false;
   HeapVector<Member<PerformanceServerTiming>> server_timing_;
 };