perfetto-ui: Add canned queries

Also fix trace_processor total CPU example query which was missing a sum.

Change-Id: I35e6a6ee863ced01943eccfce773b10e34d64c2f

docs/trace-processor.md

diff --git a/docs/trace-processor.md b/docs/trace-processor.md
index 5644457..c79d459 100644
--- a/docs/trace-processor.md
+++ b/docs/trace-processor.md
@@ -148,7 +148,10 @@
 
 ### CPU time for top 100 processes
 ``` sql
-select proc_name, cpu_sec from (select process.name as proc_name, upid, cpu_sec from (select utid, sum(dur)/1e9 as cpu_sec from sched group by utid) left join thread using(utid) left join process using(upid)) group by upid order by cpu_sec desc limit 100
+select process.name, tot_proc/1e9 as cpu_sec from (select upid, sum(tot_thd) as
+tot_proc from (select utid, sum(dur) as tot_thd from sched group by utid) join
+thread using(utid) group by upid) join process using(upid) order by cpu_sec desc
+limit 100;
 ```
 
 ### CPU time for top 100 processes broken down by cpu