[Telemetry] Allow --report-root-metrics to work on unsupported hardware.

tools/telemetry/telemetry/core/platform/mac_platform_backend.py

Index: tools/telemetry/telemetry/core/platform/mac_platform_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/mac_platform_backend.py b/tools/telemetry/telemetry/core/platform/mac_platform_backend.py
index 5f27c35c911e696a00326225c2cfa9b8df9d916b..95dbe1bd1bc747578e0385357f410cad42c2a0eb 100644
--- a/tools/telemetry/telemetry/core/platform/mac_platform_backend.py
+++ b/tools/telemetry/telemetry/core/platform/mac_platform_backend.py
@@ -201,7 +201,10 @@ class MacPlatformBackend(posix_platform_backend.PosixPlatformBackend):
       # Duration of this sample.
       sample_duration_ms = int(plist['elapsed_ns']) / 10**6
 
+      if 'processor' not in plist:
+        continue
       processor = plist['processor']
+
       energy_consumption_mw = int(processor.get('package_watts', 0)) * 10**3
 
       total_energy_consumption_mwh += (energy_consumption_mw *
@@ -212,8 +215,9 @@ class MacPlatformBackend(posix_platform_backend.PosixPlatformBackend):
     # -------- Collect and Process Data -------------
     out_dict = {}
     # Raw power usage samples.
-    out_dict['power_samples_mw'] = power_samples
-    out_dict['energy_consumption_mwh'] = total_energy_consumption_mwh
+    if power_samples:
+      out_dict['power_samples_mw'] = power_samples
+      out_dict['energy_consumption_mwh'] = total_energy_consumption_mwh
 
     return out_dict