Provide API to expose non-empty top source url.

Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I6390806935ada277db965718a804ab090b3be5dd
Reviewed-on: https://chromium-review.googlesource.com/1041157Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Commit-Queue: Hidy Han <hidyhan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53047}

include/v8-inspector.h

@@ -99,6 +99,7 @@ class V8_EXPORT V8ContextInfo {
 
 class V8_EXPORT V8StackTrace {
  public:
+  virtual StringView firstNonEmptySourceURL() const = 0;
   virtual bool isEmpty() const = 0;
   virtual StringView topSourceURL() const = 0;
   virtual int topLineNumber() const = 0;

src/inspector/v8-stack-trace-impl.cc

@@ -215,6 +215,15 @@ std::unique_ptr<V8StackTrace> V8StackTraceImpl::clone() {
       m_frames, 0, std::shared_ptr<AsyncStackTrace>(), V8StackTraceId()));
 }
 
+StringView V8StackTraceImpl::firstNonEmptySourceURL() const {
+  for (size_t i = 0; i < m_frames.size(); ++i) {
+    if (m_frames[i]->sourceURL().length()) {
+      return toStringView(m_frames[i]->sourceURL());
+    }
+  }
+  return StringView();
+}
+
 bool V8StackTraceImpl::isEmpty() const { return m_frames.empty(); }
 
 StringView V8StackTraceImpl::topSourceURL() const {

src/inspector/v8-stack-trace-impl.h

@@ -64,6 +64,7 @@ class V8StackTraceImpl : public V8StackTrace {
   // V8StackTrace implementation.
   // This method drops the async stack trace.
   std::unique_ptr<V8StackTrace> clone() override;
+  StringView firstNonEmptySourceURL() const override;
   bool isEmpty() const override;
   StringView topSourceURL() const override;
   int topLineNumber() const override;    // 1-based.