Support narrowing a cpu profile to a given time window

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index ff0139352ea39069273b0c5a90167f2d4809a135..4d30ba4c129f3a804e671f055e72b44f8baa75e8 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -296,6 +296,18 @@ bool ReturnAddressLocator::LocateReturnAddress(uword* return_address) {
 #endif
 
 
+bool SampleFilter::TimeFilterSample(Sample* sample) {
+  if ((time_origin_micros_ == -1) ||
+      (time_extent_micros_ == -1)) {
+    // No time filter passed in, always pass.
+    return true;
+  }
+  const int64_t timestamp = sample->timestamp();
+  int64_t delta = timestamp - time_origin_micros_;
+  return (delta >= 0) && (delta < time_extent_micros_);
+}
+
+
 ClearProfileVisitor::ClearProfileVisitor(Isolate* isolate)
     : SampleVisitor(isolate) {
 }
@@ -1208,6 +1220,10 @@ ProcessedSampleBuffer* SampleBuffer::BuildProcessedSampleBuffer(
       // No frames.
       continue;
     }
+    if (!filter->TimeFilterSample(sample)) {
+      // Did not pass time filter.
+      continue;
+    }
     if (!filter->FilterSample(sample)) {
       // Did not pass filter.
       continue;