Keep screen on when there is an active WebRTC session on Android.

content/browser/power_save_blocker_android.cc

Index: content/browser/power_save_blocker_android.cc
===================================================================
--- content/browser/power_save_blocker_android.cc	(revision 201139)
+++ content/browser/power_save_blocker_android.cc	(working copy)
@@ -5,24 +5,67 @@
 #include "content/browser/power_save_blocker_impl.h"
 
 #include "base/logging.h"
+#include "content/browser/android/content_video_view.h"
+#include "content/public/browser/browser_thread.h"
 
 namespace content {
 
 class PowerSaveBlockerImpl::Delegate
-    : public base::RefCounted<PowerSaveBlockerImpl::Delegate> {
+    : public base::RefCountedThreadSafe<PowerSaveBlockerImpl::Delegate> {
+ public:
+  explicit Delegate(PowerSaveBlockerType type) : type_(type) {}
+
+  // Does the actual work to apply or remove the desired power save block.
+  void ApplyBlock();
+  void RemoveBlock();
+
  private:
-  friend class base::RefCounted<Delegate>;
+  friend class base::RefCountedThreadSafe<Delegate>;
   ~Delegate() {}
+
+  // The counter of requests from clients for type
+  // kPowerSaveBlockPreventDisplaySleep.
+  static int blocker_count_;
+  const PowerSaveBlockerType type_;
+
+  DISALLOW_COPY_AND_ASSIGN(Delegate);
 };
 
+int PowerSaveBlockerImpl::Delegate::blocker_count_ = 0;
+
+void PowerSaveBlockerImpl::Delegate::ApplyBlock() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (type_ != kPowerSaveBlockPreventDisplaySleep)
+    return;
+
+  if (blocker_count_ == 0)
+    ContentVideoView::KeepScreenOn(true);
+  ++blocker_count_;
+}
+
+void PowerSaveBlockerImpl::Delegate::RemoveBlock() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (type_ != kPowerSaveBlockPreventDisplaySleep)
+    return;
+
+  --blocker_count_;
+  if (blocker_count_ == 0)
+    ContentVideoView::KeepScreenOn(false);
+}
+
 PowerSaveBlockerImpl::PowerSaveBlockerImpl(PowerSaveBlockerType type,
-                                           const std::string& reason) {
-  // TODO(wangxianzhu): Implement it.
+                                           const std::string& reason)
+    : delegate_(new Delegate(type)) {
   // This may be called on any thread.
-  NOTIMPLEMENTED();
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&Delegate::ApplyBlock, delegate_));
 }
 
 PowerSaveBlockerImpl::~PowerSaveBlockerImpl() {
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&Delegate::RemoveBlock, delegate_));
 }
 
 }  // namespace content