Fix incorrect static method call.

cpuMonitor is actually null at the time of the call, but it works
because isSupported doesn't touch 'this' (being a static call).

Bug: None
Change-Id: I177807ee04075d16356878ec72262546d0547aa1
Reviewed-on: https://webrtc-review.googlesource.com/51861
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21983}

examples/androidapp/src/org/appspot/apprtc/CallActivity.java

@@ -355,7 +355,7 @@ public class CallActivity extends Activity implements AppRTCClient.SignalingEven
         new RoomConnectionParameters(roomUri.toString(), roomId, loopback, urlParameters);
 
     // Create CPU monitor
-    if (cpuMonitor.isSupported()) {
+    if (CpuMonitor.isSupported()) {
       cpuMonitor = new CpuMonitor(this);
       hudFragment.setCpuMonitor(cpuMonitor);
     }