Update PowerSaveBlocker APIs design.

atom/browser/api/atom_api_power_save_blocker.cc

@@ -10,6 +10,12 @@
 
 #include "atom/common/node_includes.h"
 
+namespace {
+
+const char kPowerSaveBlockerDescription[] = "Electron";
+
+}  // namespace
+
 namespace mate {
 
 template<>
@@ -47,28 +53,64 @@ PowerSaveBlocker::PowerSaveBlocker() {
 PowerSaveBlocker::~PowerSaveBlocker() {
 }
 
-void PowerSaveBlocker::Start(
+void PowerSaveBlocker::UpdatePowerSaveBlocker() {
+  if (power_save_blocker_types_.empty()) {
+    power_save_blocker_.reset();
+    return;
+  }
+
+  // |kPowerSaveBlockPreventAppSuspension| keeps system active, but allows
+  // screen to be turned off.
+  // |kPowerSaveBlockPreventDisplaySleep| keeps system and screen active, has a
+  // higher precedence level than |kPowerSaveBlockPreventAppSuspension|.
+  //
+  // Only the highest-precedence blocker type takes effect.
+  content::PowerSaveBlocker::PowerSaveBlockerType new_blocker_type =
+      content::PowerSaveBlocker::kPowerSaveBlockPreventAppSuspension;
+  for (const auto& element : power_save_blocker_types_) {
+    if (element.second ==
+        content::PowerSaveBlocker::kPowerSaveBlockPreventDisplaySleep) {
+      new_blocker_type =
+          content::PowerSaveBlocker::kPowerSaveBlockPreventDisplaySleep;
+      break;
+    }
+  }
+
+  if (!power_save_blocker_ || new_blocker_type != current_blocker_type_) {
+    scoped_ptr<content::PowerSaveBlocker> new_blocker =
+        content::PowerSaveBlocker::Create(
+            new_blocker_type,
+            content::PowerSaveBlocker::kReasonOther,
+            kPowerSaveBlockerDescription);
+    power_save_blocker_.swap(new_blocker);
+    current_blocker_type_ = new_blocker_type;
+  }
+}
+
+int PowerSaveBlocker::Start(
     content::PowerSaveBlocker::PowerSaveBlockerType type) {
-  power_save_blocker_ = content::PowerSaveBlocker::Create(
-      type,
-      content::PowerSaveBlocker::kReasonOther,
-      "Users required");
+  static int count = 0;
+  power_save_blocker_types_[count] = type;
+  UpdatePowerSaveBlocker();
+  return count++;
 }
 
-void PowerSaveBlocker::Stop() {
-  power_save_blocker_.reset();
+bool PowerSaveBlocker::Stop(int id) {
+  bool success = power_save_blocker_types_.erase(id) > 0;
+  UpdatePowerSaveBlocker();
+  return success;
 }
 
-bool PowerSaveBlocker::IsStarted() {
-  return power_save_blocker_.get() != NULL;
+bool PowerSaveBlocker::IsStarted(int id) {
+  return power_save_blocker_types_.find(id) != power_save_blocker_types_.end();
 }
 
 mate::ObjectTemplateBuilder PowerSaveBlocker::GetObjectTemplateBuilder(
     v8::Isolate* isolate) {
   return mate::ObjectTemplateBuilder(isolate)
       .SetMethod("start", &PowerSaveBlocker::Start)
-      .SetMethod("stop", &PowerSaveBlocker::Stop);
-      .SetMethod("isStarted", &PowerSaveBlocker::IsStarted)
+      .SetMethod("stop", &PowerSaveBlocker::Stop)
+      .SetMethod("isStarted", &PowerSaveBlocker::IsStarted);
 }
 
 // static

atom/browser/api/atom_api_power_save_blocker.h

@@ -5,6 +5,8 @@
 #ifndef ATOM_BROWSER_API_ATOM_API_POWER_SAVE_BLOCKER_H_
 #define ATOM_BROWSER_API_ATOM_API_POWER_SAVE_BLOCKER_H_
 
+#include <map>
+
 #include "base/memory/scoped_ptr.h"
 #include "content/public/browser/power_save_blocker.h"
 #include "native_mate/handle.h"
@@ -31,11 +33,22 @@ class PowerSaveBlocker : public mate::Wrappable {
       v8::Isolate* isolate) override;
 
  private:
-  void Start(content::PowerSaveBlocker::PowerSaveBlockerType type);
-  void Stop();
-  bool IsStarted();
+  void UpdatePowerSaveBlocker();
+  int Start(content::PowerSaveBlocker::PowerSaveBlockerType type);
+  bool Stop(int id);
+  bool IsStarted(int id);
 
   scoped_ptr<content::PowerSaveBlocker> power_save_blocker_;
+
+  // Currnet blocker type used by |power_save_blocker_|
+  content::PowerSaveBlocker::PowerSaveBlockerType current_blocker_type_;
+
+  // Map from id to the corresponding blocker type for each request.
+  typedef std::map<int, content::PowerSaveBlocker::PowerSaveBlockerType>
+      PowerSaveBlockerTypeMap;
+  PowerSaveBlockerTypeMap power_save_blocker_types_;
+
+
   DISALLOW_COPY_AND_ASSIGN(PowerSaveBlocker);
 };