Plugin Power Saver: Mute throttled plugins.

BUG=452215, 403800

Review URL: https://codereview.chromium.org/879403002

Cr-Commit-Position: refs/heads/master@{#321593}

5 files changed, 113 insertions, 10 deletions

diff --git a/content/public/renderer/plugin_instance_throttler.h b/content/public/renderer/plugin_instance_throttler.h
index d20f525..f9c5b92 100644
--- a/content/public/renderer/plugin_instance_throttler.h
+++ b/content/public/renderer/plugin_instance_throttler.h
@@ -84,6 +84,10 @@ class CONTENT_EXPORT PluginInstanceThrottler {
 
   virtual blink::WebPlugin* GetWebPlugin() const = 0;
 
+  // Throttler needs to know when the plugin audio is throttled, as this may
+  // prevent the plugin from generating new frames.
+  virtual void NotifyAudioThrottled() = 0;
+
  protected:
   PluginInstanceThrottler() {}
 
diff --git a/content/renderer/pepper/plugin_instance_throttler_impl.cc b/content/renderer/pepper/plugin_instance_throttler_impl.cc
index 097480d..6a48a4d 100644
--- a/content/renderer/pepper/plugin_instance_throttler_impl.cc
+++ b/content/renderer/pepper/plugin_instance_throttler_impl.cc
@@ -26,6 +26,11 @@ const double kAcceptableFrameMaximumBoringness = 0.94;
 
 const int kMinimumConsecutiveInterestingFrames = 4;
 
+// When plugin audio is throttled, the plugin will sometimes stop generating
+// video frames. We use this timeout to prevent waiting forever for a good
+// poster image. Chosen arbitrarily.
+const int kAudioThrottledFrameTimeoutMilliseconds = 500;
+
 }  // namespace
 
 // static
@@ -53,6 +58,13 @@ PluginInstanceThrottlerImpl::PluginInstanceThrottlerImpl(
       web_plugin_(nullptr),
       consecutive_interesting_frames_(0),
       frames_examined_(0),
+      audio_throttled_(false),
+      audio_throttled_frame_timeout_(
+          FROM_HERE,
+          base::TimeDelta::FromMilliseconds(
+              kAudioThrottledFrameTimeoutMilliseconds),
+          this,
+          &PluginInstanceThrottlerImpl::EngageThrottle),
       weak_factory_(this) {
 }
 
@@ -101,6 +113,11 @@ blink::WebPlugin* PluginInstanceThrottlerImpl::GetWebPlugin() const {
   return web_plugin_;
 }
 
+void PluginInstanceThrottlerImpl::NotifyAudioThrottled() {
+  audio_throttled_ = true;
+  audio_throttled_frame_timeout_.Reset();
+}
+
 void PluginInstanceThrottlerImpl::SetWebPlugin(blink::WebPlugin* web_plugin) {
   DCHECK(!web_plugin_);
   web_plugin_ = web_plugin;
@@ -148,9 +165,14 @@ void PluginInstanceThrottlerImpl::OnImageFlush(const SkBitmap* bitmap) {
   else
     consecutive_interesting_frames_ = 0;
 
+  // Does not make a copy, just takes a reference to the underlying pixel data.
+  last_received_frame_ = *bitmap;
+
+  if (audio_throttled_)
+    audio_throttled_frame_timeout_.Reset();
+
   if (frames_examined_ >= kMaximumFramesToExamine ||
       consecutive_interesting_frames_ >= kMinimumConsecutiveInterestingFrames) {
-    FOR_EACH_OBSERVER(Observer, observer_list_, OnKeyframeExtracted(bitmap));
     EngageThrottle();
   }
 }
@@ -179,6 +201,14 @@ void PluginInstanceThrottlerImpl::EngageThrottle() {
   if (state_ != THROTTLER_STATE_AWAITING_KEYFRAME)
     return;
 
+  if (!last_received_frame_.empty()) {
+    FOR_EACH_OBSERVER(Observer, observer_list_,
+                      OnKeyframeExtracted(&last_received_frame_));
+
+    // Release our reference to the underlying pixel data.
+    last_received_frame_.reset();
+  }
+
   state_ = THROTTLER_STATE_PLUGIN_THROTTLED;
   FOR_EACH_OBSERVER(Observer, observer_list_, OnThrottleStateChange());
 }
diff --git a/content/renderer/pepper/plugin_instance_throttler_impl.h b/content/renderer/pepper/plugin_instance_throttler_impl.h
index b223cd2..0bcad2f 100644
--- a/content/renderer/pepper/plugin_instance_throttler_impl.h
+++ b/content/renderer/pepper/plugin_instance_throttler_impl.h
@@ -8,9 +8,11 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
+#include "base/timer/timer.h"
 #include "content/common/content_export.h"
 #include "content/public/renderer/plugin_instance_throttler.h"
 #include "ppapi/shared_impl/ppb_view_shared.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 
 namespace blink {
 class WebInputEvent;
@@ -36,6 +38,7 @@ class CONTENT_EXPORT PluginInstanceThrottlerImpl
   void MarkPluginEssential(PowerSaverUnthrottleMethod method) override;
   void SetHiddenForPlaceholder(bool hidden) override;
   blink::WebPlugin* GetWebPlugin() const override;
+  void NotifyAudioThrottled() override;
 
   void SetWebPlugin(blink::WebPlugin* web_plugin);
 
@@ -80,6 +83,7 @@ class CONTENT_EXPORT PluginInstanceThrottlerImpl
   // simply suspend the plugin where it's at. Chosen arbitrarily.
   static const int kMaximumFramesToExamine;
 
+  void AudioThrottledFrameTimeout();
   void EngageThrottle();
 
   ThrottlerState state_;
@@ -88,12 +92,21 @@ class CONTENT_EXPORT PluginInstanceThrottlerImpl
 
   blink::WebPlugin* web_plugin_;
 
+  // Holds a reference to the last received frame. This doesn't actually copy
+  // the pixel data, but rather increments the reference count to the pixels.
+  SkBitmap last_received_frame_;
+
   // Number of consecutive interesting frames we've encountered.
   int consecutive_interesting_frames_;
 
   // Number of frames we've examined to find a keyframe.
   int frames_examined_;
 
+  // Video plugins with throttled audio often stop generating frames.
+  // This timer is so we don't wait forever for candidate poster frames.
+  bool audio_throttled_;
+  base::DelayTimer<PluginInstanceThrottlerImpl> audio_throttled_frame_timeout_;
+
   ObserverList<Observer> observer_list_;
 
   base::WeakPtrFactory<PluginInstanceThrottlerImpl> weak_factory_;
diff --git a/content/renderer/pepper/ppb_audio_impl.cc b/content/renderer/pepper/ppb_audio_impl.cc
index b7fcf0d..7a5ead9 100644
--- a/content/renderer/pepper/ppb_audio_impl.cc
+++ b/content/renderer/pepper/ppb_audio_impl.cc
@@ -30,9 +30,24 @@ namespace content {
 // PPB_Audio_Impl --------------------------------------------------------------
 
 PPB_Audio_Impl::PPB_Audio_Impl(PP_Instance instance)
-    : Resource(ppapi::OBJECT_IS_IMPL, instance), audio_(NULL) {}
+    : Resource(ppapi::OBJECT_IS_IMPL, instance),
+      audio_(NULL),
+      playback_throttled_(false) {
+  PepperPluginInstanceImpl* plugin_instance =
+      static_cast<PepperPluginInstanceImpl*>(
+          PepperPluginInstance::Get(pp_instance()));
+  if (plugin_instance && plugin_instance->throttler()) {
+    plugin_instance->throttler()->AddObserver(this);
+  }
+}
 
 PPB_Audio_Impl::~PPB_Audio_Impl() {
+  PepperPluginInstanceImpl* instance = static_cast<PepperPluginInstanceImpl*>(
+      PepperPluginInstance::Get(pp_instance()));
+  if (instance && instance->throttler()) {
+    instance->throttler()->RemoveObserver(this);
+  }
+
   // Calling ShutDown() makes sure StreamCreated cannot be called anymore and
   // releases the audio data associated with the pointer. Note however, that
   // until ShutDown returns, StreamCreated may still be called. This will be
@@ -57,6 +72,17 @@ PP_Bool PPB_Audio_Impl::StartPlayback() {
     return PP_FALSE;
   if (playing())
     return PP_TRUE;
+
+  // If plugin is in power saver mode, defer audio IPC communication.
+  PepperPluginInstanceImpl* instance = static_cast<PepperPluginInstanceImpl*>(
+      PepperPluginInstance::Get(pp_instance()));
+  if (instance && instance->throttler() &&
+      instance->throttler()->power_saver_enabled()) {
+    instance->throttler()->NotifyAudioThrottled();
+    playback_throttled_ = true;
+    return PP_TRUE;
+  }
+
   SetStartPlaybackState();
   return PP_FromBool(audio_->StartPlayback());
 }
@@ -64,11 +90,19 @@ PP_Bool PPB_Audio_Impl::StartPlayback() {
 PP_Bool PPB_Audio_Impl::StopPlayback() {
   if (!audio_)
     return PP_FALSE;
+
+  if (playback_throttled_) {
+    // If a start playback request is still deferred, we must fulfill it first
+    // to shut down the audio thread correctly.
+    StartDeferredPlayback();
+  }
+
   if (!playing())
     return PP_TRUE;
   if (!audio_->StopPlayback())
     return PP_FALSE;
   SetStopPlaybackState();
+
   return PP_TRUE;
 }
 
@@ -85,13 +119,6 @@ int32_t PPB_Audio_Impl::Open(PP_Resource config,
   if (!instance)
     return PP_ERROR_FAILED;
 
-  // Prevent any throttling since we are playing audio. This stopgap prevents
-  // video from appearing 'frozen' while the audio track plays.
-  if (instance->throttler() && instance->throttler()->power_saver_enabled()) {
-    instance->throttler()->MarkPluginEssential(
-        PluginInstanceThrottler::UNTHROTTLE_METHOD_BY_AUDIO);
-  }
-
   // When the stream is created, we'll get called back on StreamCreated().
   DCHECK(!audio_);
   audio_ = PepperPlatformAudioOutput::Create(
@@ -132,4 +159,22 @@ void PPB_Audio_Impl::OnSetStreamInfo(
                 enter.object()->GetSampleFrameCount());
 }
 
+void PPB_Audio_Impl::OnThrottleStateChange() {
+  PepperPluginInstanceImpl* instance = static_cast<PepperPluginInstanceImpl*>(
+      PepperPluginInstance::Get(pp_instance()));
+  if (playback_throttled_ && instance && instance->throttler() &&
+      !instance->throttler()->power_saver_enabled()) {
+    // If we have become unthrottled, and we have a pending playback, start it.
+    StartDeferredPlayback();
+  }
+}
+
+void PPB_Audio_Impl::StartDeferredPlayback() {
+  DCHECK(playback_throttled_);
+  playback_throttled_ = false;
+
+  SetStartPlaybackState();
+  audio_->StartPlayback();
+}
+
 }  // namespace content
diff --git a/content/renderer/pepper/ppb_audio_impl.h b/content/renderer/pepper/ppb_audio_impl.h
index 3348527..6c0af8f 100644
--- a/content/renderer/pepper/ppb_audio_impl.h
+++ b/content/renderer/pepper/ppb_audio_impl.h
@@ -9,6 +9,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/shared_memory.h"
 #include "base/sync_socket.h"
+#include "content/public/renderer/plugin_instance_throttler.h"
 #include "content/renderer/pepper/audio_helper.h"
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/ppb_audio.h"
@@ -28,7 +29,8 @@ class PepperPlatformAudioOutput;
 // to look more like typical HostResource implementations.
 class PPB_Audio_Impl : public ppapi::Resource,
                        public ppapi::PPB_Audio_Shared,
-                       public AudioHelper {
+                       public AudioHelper,
+                       public PluginInstanceThrottler::Observer {
  public:
   explicit PPB_Audio_Impl(PP_Instance instance);
 
@@ -52,6 +54,12 @@ class PPB_Audio_Impl : public ppapi::Resource,
                        size_t shared_memory_size_,
                        base::SyncSocket::Handle socket) override;
 
+  // PluginInstanceThrottler::Observer implementation.
+  void OnThrottleStateChange() override;
+
+  // Starts the deferred playback and unsubscribes from the throttler.
+  void StartDeferredPlayback();
+
   // AudioConfig used for creating this Audio object. We own a ref.
   ppapi::ScopedPPResource config_;
 
@@ -59,6 +67,9 @@ class PPB_Audio_Impl : public ppapi::Resource,
   // own this pointer but are responsible for calling Shutdown on it.
   PepperPlatformAudioOutput* audio_;
 
+  // Stream is playing, but throttled due to Plugin Power Saver.
+  bool playback_throttled_;
+
   DISALLOW_COPY_AND_ASSIGN(PPB_Audio_Impl);
 };