Fix a bug where Guest Profiles in CrOS could cause crashes when collecting

chrome/browser/power/process_power_collector.cc

Index: chrome/browser/power/process_power_collector.cc
diff --git a/chrome/browser/power/process_power_collector.cc b/chrome/browser/power/process_power_collector.cc
index 5d44e6112f3a1e8870446ed23964218a238fbe48..325541470897922f5129b1484f06adb9733ce870 100644
--- a/chrome/browser/power/process_power_collector.cc
+++ b/chrome/browser/power/process_power_collector.cc
@@ -171,7 +171,8 @@ void ProcessPowerCollector::RecordCpuUsageByOrigin(double total_cpu_percent) {
     power::OriginPowerMap* origin_power_map =
         power::OriginPowerMapFactory::GetForBrowserContext(
             it->second->profile());
-    DCHECK(origin_power_map);
+    if (!origin_power_map)

[Daniel Erat, 2014/09/19 00:39:42]

nit: add a comment documenting that this can happen in chrome os guest mode?

[Daniel Nishi, 2014/09/19 00:50:15]

Done.

+      continue;
     origin_power_map->AddPowerForOrigin(origin, last_process_power_usage);
   }
 
@@ -183,6 +184,8 @@ void ProcessPowerCollector::RecordCpuUsageByOrigin(double total_cpu_percent) {
        ++it) {
     power::OriginPowerMap* origin_power_map =
         power::OriginPowerMapFactory::GetForBrowserContext(*it);
+    if (!origin_power_map)
+      continue;
     origin_power_map->OnAllOriginsUpdated();
   }
 }