PerformanceMonitor: UMA alert for high browser CPU usage.

chrome/browser/performance_monitor/constants.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_PERFORMANCE_MONITOR_CONSTANTS_H_
 #define CHROME_BROWSER_PERFORMANCE_MONITOR_CONSTANTS_H_
 
 #include "base/basictypes.h"
 #include "base/time/time.h"
 
 namespace performance_monitor {
 
 // Constants which are used by the PerformanceMonitor and its related classes.
 // The constants should be documented alongside the definition of their values
 // in the .cc file.
 
 extern const char kMetricNotFoundError[];
 extern const char kProcessChromeAggregate[];
 
 // State tokens
 extern const char kStateChromeVersion[];
 extern const char kStateProfilePrefix[];
 
+// The interval the watched processes are sampled for performance metrics.
+const int kSampleIntervalInSeconds = 10;
 // The default interval at which PerformanceMonitor performs its timed
 // collections; this can be overridden by using the kPerformanceMonitorGathering
 // switch with an associated (positive integer) value.
 const int kDefaultGatherIntervalInSeconds = 120;
 
 // Unit values (for use in metric, and on the UI side).
 
 // Memory measurements
 const int64 kBytesPerKilobyte = 1 << 10;
 const int64 kBytesPerMegabyte = kBytesPerKilobyte * (1 << 10);
 const int64 kBytesPerGigabyte = kBytesPerMegabyte * (1 << 10);
 const int64 kBytesPerTerabyte = kBytesPerGigabyte * (1 << 10);
 
 // Time measurements - Most of these are imported from base/time/time.h
 // These units are used for display (and it's related calculations), not for
 // any mathematical analysis. Thus we can estimate for values without an exact
 // conversion.
 const int64 kMicrosecondsPerMonth = base::Time::kMicrosecondsPerDay * 30;
 const int64 kMicrosecondsPerYear = base::Time::kMicrosecondsPerDay * 365;
 
+// Performance alert thresholds
+
+// If a process is consistently above this CPU utilization percentage over time,
+// we consider it as high and may take action.
+const float kHighCPUUtilizationThreshold = 90.0f;
 }  // namespace performance_monitor
 
 #endif  // CHROME_BROWSER_PERFORMANCE_MONITOR_CONSTANTS_H_