Adds a bar below the current timeline view which can show the time
when an individual function was on the stack. Functions in the call
stack are now clickable to show them in this view.
Sections where the function was on the stack, but not at the top, are
displayed at half height.
Review-Url: https://codereview.chromium.org/2737083003
Cr-Commit-Position: refs/heads/master@{#43673}
The function list is now filtered by category by default, and sorting improved to break ties better.
Since the butterfly trees get massive, I had to start expanding the call trees on demand. This is implemented by keeping track of all ticks that cross given tree node (+ position where they crosses it). This seems to work quite well - in subsequent CL, I am planning to flip the bottom-up and top-down trees to use this.
Review-Url: https://codereview.chromium.org/2730293002
Cr-Commit-Position: refs/heads/master@{#43602}
