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)
@@ -4,25 +4,73 @@
 
 #include "content/browser/power_save_blocker_impl.h"
 
+#include "base/atomicops.h"
 #include "base/logging.h"
+#include "content/browser/android/content_video_view.h"
+#include "content/public/browser/browser_thread.h"
 
 namespace content {
+namespace {
+base::subtle::Atomic32 g_blocker_count = 0;
+}  // namespace
 
 class PowerSaveBlockerImpl::Delegate
-    : public base::RefCounted<PowerSaveBlockerImpl::Delegate> {
+    : public base::RefCountedThreadSafe<PowerSaveBlockerImpl::Delegate> {
+ public:
+  Delegate(PowerSaveBlockerType type, const std::string& reason)
+      : type_(type), reason_(reason) {}
+
+  // Does the actual work to apply or remove the desired power save block.
+  void ApplyBlock();
+  void RemoveBlock();
+
+  PowerSaveBlockerType type() { return type_; }
+
  private:
-  friend class base::RefCounted<Delegate>;
+  friend class base::RefCountedThreadSafe<Delegate>;
   ~Delegate() {}
+
+  PowerSaveBlockerType type_;
+  const std::string reason_;

[qinmin, 2013/05/21 17:18:40]

nit: you can remove this, not being used

+
+  DISALLOW_COPY_AND_ASSIGN(Delegate);
 };
 
+void PowerSaveBlockerImpl::Delegate::ApplyBlock() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  ContentVideoView::KeepScreenOn(true);
+}
+
+void PowerSaveBlockerImpl::Delegate::RemoveBlock() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  ContentVideoView::KeepScreenOn(false);
+}
+
 PowerSaveBlockerImpl::PowerSaveBlockerImpl(PowerSaveBlockerType type,
-                                           const std::string& reason) {
-  // TODO(wangxianzhu): Implement it.
+                                           const std::string& reason)
+    : delegate_(new Delegate(type, reason)) {
   // This may be called on any thread.
-  NOTIMPLEMENTED();
+  if (type == kPowerSaveBlockPreventDisplaySleep) {
+    int32 count = base::subtle::NoBarrier_AtomicIncrement(&g_blocker_count, 1);
+    DCHECK_GT(count, 0);
+    if (count == 1) {

[qinmin, 2013/05/21 14:49:56]

hmm...I think you don't need the global here. You can just use a static member
variable in Delegate, and check if it is 0 or 1 when applyblock() and
removeblock() are called. Delegate always live on the UI thread and it is
threadsafe, so there will be no race conditions.

+      BrowserThread::PostTask(
+          BrowserThread::UI, FROM_HERE,
+          base::Bind(&Delegate::ApplyBlock, delegate_));
+    }
+  }
 }
 
 PowerSaveBlockerImpl::~PowerSaveBlockerImpl() {
+  if (delegate_->type() == kPowerSaveBlockPreventDisplaySleep) {
+    int32 count = base::subtle::NoBarrier_AtomicIncrement(&g_blocker_count, -1);
+    DCHECK_GE(count, 0);
+    if (count == 0) {
+      BrowserThread::PostTask(
+          BrowserThread::UI, FROM_HERE,
+          base::Bind(&Delegate::RemoveBlock, delegate_));
+    }
+  }
 }
 
 }  // namespace content