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

chrome/browser/power/process_power_collector.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/power/process_power_collector.h"
 
 #include "base/process/process_handle.h"
 #include "base/process/process_metrics.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 153 matching lines @@
   for (ProcessMetricsMap::iterator it = metrics_map_.begin();
        it != metrics_map_.end();
        ++it) {
     double last_process_power_usage = it->second->last_cpu_percent();
     last_process_power_usage *= scale_factor_ / total_cpu_percent;
 
     GURL origin = it->second->last_origin();
     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);
   }
 
   // Iterate over all profiles to let them know we've finished updating.
   ProfileManager* pm = g_browser_process->profile_manager();
   std::vector<Profile*> open_profiles = pm->GetLoadedProfiles();
   for (std::vector<Profile*>::const_iterator it = open_profiles.begin();
        it != open_profiles.end();
        ++it) {
     power::OriginPowerMap* origin_power_map =
         power::OriginPowerMapFactory::GetForBrowserContext(*it);
+    if (!origin_power_map)
+      continue;
     origin_power_map->OnAllOriginsUpdated();
   }
 }
 
 void ProcessPowerCollector::UpdateProcessInMap(
     const content::RenderProcessHost* rph,
     const GURL& origin) {
   base::ProcessHandle handle = rph->GetHandle();
   if (metrics_map_.find(handle) == metrics_map_.end()) {
     metrics_map_[handle] = linked_ptr<PerProcessData>(new PerProcessData(
 #if defined(OS_MACOSX)
         scoped_ptr<base::ProcessMetrics>(
             base::ProcessMetrics::CreateProcessMetrics(handle, NULL)),
 #else
         scoped_ptr<base::ProcessMetrics>(
             base::ProcessMetrics::CreateProcessMetrics(handle)),
 #endif
         origin,
         Profile::FromBrowserContext(rph->GetBrowserContext())));
   }
 
   linked_ptr<PerProcessData>& process_data = metrics_map_[handle];
   process_data->set_last_cpu_percent(std::max(0.0,
       cpu_usage_callback_.is_null() ? process_data->metrics()->GetCPUUsage()
                                     : cpu_usage_callback_.Run(handle)));
   process_data->set_seen_this_cycle(true);
 }