[Telemetry refactor] Migrate clients to new JavaScript API (batch 3)

tools/chrome_proxy/common/chrome_proxy_measurements.py

Index: tools/chrome_proxy/common/chrome_proxy_measurements.py
diff --git a/tools/chrome_proxy/common/chrome_proxy_measurements.py b/tools/chrome_proxy/common/chrome_proxy_measurements.py
index 36b06143f147e82a8751c073986e709b7674bddf..ad41be79d70bb537b817ba5e177a6bad07d73fa2 100644
--- a/tools/chrome_proxy/common/chrome_proxy_measurements.py
+++ b/tools/chrome_proxy/common/chrome_proxy_measurements.py
@@ -51,14 +51,16 @@ def WaitForViaHeader(tab, url="http://check.googlezip.net/test.html"):
     '</body></html>'))
 
   # Ensure the page has finished loading before attempting the DRP check.
-  tab.WaitForJavaScriptExpression('performance.timing.loadEventEnd', 60)
+  tab.WaitForJavaScriptCondition2('performance.timing.loadEventEnd', timeout=60)
 
   expected_via_header = metrics.CHROME_PROXY_VIA_HEADER
   if ChromeProxyValidation.extra_via_header:
     expected_via_header = ChromeProxyValidation.extra_via_header
 
-  tab.WaitForJavaScriptExpression(
-      'PollDRPCheck("%s", "%s")' % (url, expected_via_header), 60)
+  tab.WaitForJavaScriptCondition2(
+      'PollDRPCheck({{ url }}, {{ via_header }})',
+      url=url, via_header=expected_via_header,
+      timeout=60)
 
 
 class ChromeProxyValidation(legacy_page_test.LegacyPageTest):
@@ -100,7 +102,8 @@ class ChromeProxyValidation(legacy_page_test.LegacyPageTest):
   def ValidateAndMeasurePage(self, page, tab, results):
     self._page = page
     # Wait for the load event.
-    tab.WaitForJavaScriptExpression('performance.timing.loadEventStart', 300)
+    tab.WaitForJavaScriptCondition2(
+        'performance.timing.loadEventStart', timeout=300)
     assert self._metrics
     self._metrics.Stop(page, tab)
     if ChromeProxyValidation.extra_via_header: