Update cpu and memory metric calculation and several small improvements.

chrome/test/media_router/telemetry/media_router_config.py

Index: chrome/test/media_router/telemetry/media_router_config.py
diff --git a/chrome/test/media_router/telemetry/media_router_config.py b/chrome/test/media_router/telemetry/media_router_config.py
index 469ba8bc0f3a8c255343d92024c57428f7a23fa5..2c06ff77864c751801854a372cd1158be22720d8 100644
--- a/chrome/test/media_router/telemetry/media_router_config.py
+++ b/chrome/test/media_router/telemetry/media_router_config.py
@@ -10,6 +10,10 @@ sys.path.append(os.path.join(os.path.dirname(__file__),
                              os.pardir, os.pardir, os.pardir,
                              os.pardir, 'tools', 'perf'))
 
+# Add //chrome/test/media_router/internal to system path.
+sys.path.append(os.path.join(os.path.dirname(__file__),
+                                 os.pardir, 'internal'))
+
 from chrome_telemetry_build import chromium_config
 
 TELEMETRY_DIR = chromium_config.GetTelemetryDir()