[telemetry] Disable measuring renderer CPU usage.

They're causing failures on the bots, and are incorrect anyway.

BUG=419786
TEST=None.

Review URL: https://codereview.chromium.org/671713004

Cr-Commit-Position: refs/heads/master@{#301549}

tools/telemetry/telemetry/core/browser.py

@@ -212,6 +212,11 @@ class Browser(app.App):
     result = self._GetStatsCommon(self._platform_backend.GetCpuStats)
     del result['ProcessCount']
 
+    # FIXME: Renderer process CPU times are impossible to compare correctly.
+    # http://crbug.com/419786#c11
+    if 'Renderer' in result:
+      del result['Renderer']
+
     # We want a single time value, not the sum for all processes.
     cpu_timestamp = self._platform_backend.GetCpuTimestamp()
     for process_type in result: