[WIP] [DEFINITELY NOT READY TO LAND] Cpu time metric implementation

tracing/tracing/model/thread.html

Index: tracing/tracing/model/thread.html
diff --git a/tracing/tracing/model/thread.html b/tracing/tracing/model/thread.html
index 736345d5f43b0adcb47f690c3a9a89cdacea8a57..c25f69fd032b7980067a991e266f649abc54dccf 100644
--- a/tracing/tracing/model/thread.html
+++ b/tracing/tracing/model/thread.html
@@ -300,6 +300,27 @@ tr.exportTo('tr.model', function() {
     get samples() {
       return this.samples_;
     },
+
+    /**
+     * Returns a string that denotes the 'type' of a thread used for naming
+     * metrics and histograms.
+     *
+     * It returns the substring from beginning of the string until the first
+     * numeric character or the character '/'. Example:
+     * ThreadName12      -> ThreadName
+     * ThreadName/34123  -> ThreadName
+     * ThreadName1/34123 -> ThreadName
+     */
+    get type() {
+      const re = /^[^0-9|\/]+/;
+      const matches = re.exec(this.name);
+      if (matches && matches[0]) return matches[0];
+
+      // If a thread is named 42GPU, let's not try to find its type.
+      // We should fix the thread name.
+      throw new Error('Could not determine thread type for thread name ' +
+          this.name);
+    }
   };
 
   /**