Learn how things work by looking at and running tests.
// test/cctest/test-cpu-profiler.cc
[..]
unsigned int line_count = func_node->GetHitLineCount();
CHECK_EQ(2u, line_count); // Expect two hit source lines - #1 and #5.
ScopedVector<v8::CpuProfileNode::LineTick> entries(line_count);
CHECK(func_node->GetLineTicks(&entries[0], line_count));
int value = 0;
for (int i = 0; i < entries.length(); i++)
if (entries[i].line == hit_line) {
value = entries[i].hit_count;
break;
}
CHECK_EQ(hit_count, value);