[Telemetry] Allow memory info to go missing on non-rooted devices.

tools/telemetry/telemetry/core/platform/proc_supporting_platform_backend.py

Index: tools/telemetry/telemetry/core/platform/proc_supporting_platform_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/proc_supporting_platform_backend.py b/tools/telemetry/telemetry/core/platform/proc_supporting_platform_backend.py
index 8a7ddd0d81593fd16f8825b97c2a98c684106e4b..8633b4301eda2b1c5ccbd0d879d1f6cbe9f6244e 100644
--- a/tools/telemetry/telemetry/core/platform/proc_supporting_platform_backend.py
+++ b/tools/telemetry/telemetry/core/platform/proc_supporting_platform_backend.py
@@ -21,6 +21,8 @@ class ProcSupportingPlatformBackend(platform_backend.PlatformBackend):
   def GetSystemCommitCharge(self):
     meminfo_contents = self._GetFileContents('/proc/meminfo')
     meminfo = self._GetProcFileDict(meminfo_contents)
+    if not meminfo:
+      return None
     return (self._ConvertKbToByte(meminfo['MemTotal'])
             - self._ConvertKbToByte(meminfo['MemFree'])
             - self._ConvertKbToByte(meminfo['Buffers'])
@@ -30,6 +32,8 @@ class ProcSupportingPlatformBackend(platform_backend.PlatformBackend):
   def GetSystemTotalPhysicalMemory(self):
     meminfo_contents = self._GetFileContents('/proc/meminfo')
     meminfo = self._GetProcFileDict(meminfo_contents)
+    if not meminfo:
+      return None
     return self._ConvertKbToByte(meminfo['MemTotal'])
 
   def GetCpuStats(self, pid):