Support narrowing a cpu profile to a given time window

runtime/vm/profiler.h

Index: runtime/vm/profiler.h
diff --git a/runtime/vm/profiler.h b/runtime/vm/profiler.h
index e598e70089d75d8ad5766630e318a95255869f26..febff47b1a53344b3e2af89e95e2357268b46334 100644
--- a/runtime/vm/profiler.h
+++ b/runtime/vm/profiler.h
@@ -91,7 +91,12 @@ class SampleVisitor : public ValueObject {
 
 class SampleFilter : public ValueObject {
  public:
-  explicit SampleFilter(Isolate* isolate) : isolate_(isolate) { }
+  explicit SampleFilter(Isolate* isolate,
+                        int64_t time_origin_micros = -1,
+                        int64_t time_extent_micros = -1)

[siva, 2015/12/21 20:43:27]

I don't see any place where SampleFilter is constructed with just one argument
passed in, why not make time_origin_micros and time_extent_micros regular params
without any default values?

[Cutch, 2015/12/21 22:07:38]

Done.

+      : isolate_(isolate),
+        time_origin_micros_(time_origin_micros),
+        time_extent_micros_(time_extent_micros) { }

[siva, 2015/12/21 20:43:28]

ASSERT(time_origin_micros >= 0);
ASSERT(time_extent_micros >= 0);

because of the math done in the implementation of TimeFilterSample

[Cutch, 2015/12/21 22:07:38]

When these are -1 it means we don't have a TimeFilterSample.

[siva, 2015/12/22 17:08:23]

Sorry I meant :
ASSERT(time_origin_micros >= -1);
ASSERT(time_extent_micros >= -1);

   virtual ~SampleFilter() { }
 
   // Override this function.
@@ -104,8 +109,14 @@ class SampleFilter : public ValueObject {
     return isolate_;
   }
 
+  // Returns |true| if |sample| passes the time filter.
+  bool TimeFilterSample(Sample* sample);
+
  private:
   Isolate* isolate_;
+
+  int64_t time_origin_micros_;
+  int64_t time_extent_micros_;
 };