media: Update logging to indicate that new key has been provided

When playing encrypted media and decrypting stalls due to missing key,
add a message to indicate when a key is added and decryption tries to
start again.

BUG=645304
TEST=checked chrome://media-internals

Review-Url: https://codereview.chromium.org/2334953002
Cr-Commit-Position: refs/heads/master@{#419365}

media/filters/decrypting_audio_decoder.cc

@@ -278,6 +278,8 @@ void DecryptingAudioDecoder::DeliverFrame(
 
     if (need_to_try_again_if_nokey_is_returned) {
       // The |state_| is still kPendingDecode.
+      MEDIA_LOG(INFO, media_log_) << GetDisplayName()
+                                  << ": key was added, resuming decode";
       DecodePendingBuffer();
       return;
     }
@@ -320,6 +322,8 @@ void DecryptingAudioDecoder::OnKeyAdded() {
   }
 
   if (state_ == kWaitingForKey) {
+    MEDIA_LOG(INFO, media_log_) << GetDisplayName()
+                                << ": key added, resuming decode";
     state_ = kPendingDecode;
     DecodePendingBuffer();
   }

media/filters/decrypting_demuxer_stream.cc

@@ -305,6 +305,8 @@ void DecryptingDemuxerStream::DeliverBuffer(
 
     if (need_to_try_again_if_nokey) {
       // The |state_| is still kPendingDecrypt.
+      MEDIA_LOG(INFO, media_log_) << GetDisplayName()
+                                  << ": key was added, resuming decrypt";
       DecryptPendingBuffer();
       return;
     }
@@ -335,6 +337,8 @@ void DecryptingDemuxerStream::OnKeyAdded() {
   }
 
   if (state_ == kWaitingForKey) {
+    MEDIA_LOG(INFO, media_log_) << GetDisplayName()
+                                << ": key added, resuming decrypt";
     state_ = kPendingDecrypt;
     DecryptPendingBuffer();
   }

media/filters/decrypting_video_decoder.cc

@@ -255,6 +255,8 @@ void DecryptingVideoDecoder::DeliverFrame(
 
     if (need_to_try_again_if_nokey_is_returned) {
       // The |state_| is still kPendingDecode.
+      MEDIA_LOG(INFO, media_log_) << GetDisplayName()
+                                  << ": key was added, resuming decode";
       DecodePendingBuffer();
       return;
     }
@@ -299,6 +301,8 @@ void DecryptingVideoDecoder::OnKeyAdded() {
   }
 
   if (state_ == kWaitingForKey) {
+    MEDIA_LOG(INFO, media_log_) << GetDisplayName()
+                                << ": key added, resuming decode";
     state_ = kPendingDecode;
     DecodePendingBuffer();
   }