CdmAdapter: Report size of the file read by CDM via FileIO.

We report when:
1, The first time a file is fully read.
2, After the CDM throws an error with a special system code.

BUG=413812
TEST=Tested and both new UMA show in about://histograms.

Review URL: https://codereview.chromium.org/568623003

Cr-Commit-Position: refs/heads/master@{#294843}

media/cdm/ppapi/cdm_adapter.cc

@@ -19,6 +19,12 @@
 
 namespace {
 
+// Constants for UMA reporting of file size (in KB) via HistogramCustomCounts().
+// Note that the histogram is log-scaled (rather than linear).
+const uint32_t kSizeKBMin = 1;
+const uint32_t kSizeKBMax = 512 * 1024;  // 512MB
+const uint32_t kSizeKBBuckets = 100;
+
 #if !defined(NDEBUG)
   #define DLOG_TO_CONSOLE(message) LogToConsole(message);
 #else
@@ -267,7 +273,9 @@ CdmAdapter::CdmAdapter(PP_Instance instance, pp::Module* module)
       deferred_initialize_audio_decoder_(false),
       deferred_audio_decoder_config_id_(0),
       deferred_initialize_video_decoder_(false),
-      deferred_video_decoder_config_id_(0) {
+      deferred_video_decoder_config_id_(0),
+      last_read_file_size_kb_(0),
+      file_size_uma_reported_(false) {
   callback_factory_.Initialize(this);
 }
 
@@ -759,6 +767,17 @@ void CdmAdapter::OnRejectPromise(uint32_t promise_id,
                                  uint32_t system_code,
                                  const char* error_message,
                                  uint32_t error_message_length) {
+  // UMA to investigate http://crbug.com/410630
+  // TODO(xhwang): Remove after bug is fixed.
+  if (system_code == 0x27) {
+    pp::UMAPrivate uma_interface(this);
+    uma_interface.HistogramCustomCounts("Media.EME.CdmFileIO.FileSizeKBOnError",
+                                        last_read_file_size_kb_,
+                                        kSizeKBMin,
+                                        kSizeKBMax,
+                                        kSizeKBBuckets);
+  }
+
   RejectPromise(promise_id,
                 error,
                 system_code,
@@ -1082,6 +1101,25 @@ bool CdmAdapter::IsValidVideoFrame(const LinkedVideoFrame& video_frame) {
   return true;
 }
 
+void CdmAdapter::OnFirstFileRead(int32_t file_size_bytes) {
+  PP_DCHECK(IsMainThread());
+  PP_DCHECK(file_size_bytes >= 0);
+
+  last_read_file_size_kb_ = file_size_bytes / 1024;
+
+  if (file_size_uma_reported_)
+    return;
+
+  pp::UMAPrivate uma_interface(this);
+  uma_interface.HistogramCustomCounts(
+      "Media.EME.CdmFileIO.FileSizeKBOnFirstRead",
+      last_read_file_size_kb_,
+      kSizeKBMin,
+      kSizeKBMax,
+      kSizeKBBuckets);
+  file_size_uma_reported_ = true;
+}
+
 #if !defined(NDEBUG)
 void CdmAdapter::LogToConsole(const pp::Var& value) {
   PP_DCHECK(IsMainThread());
@@ -1189,7 +1227,10 @@ void CdmAdapter::OnDeferredInitializationDone(cdm::StreamType stream_type,
 
 // The CDM owns the returned object and must call FileIO::Close() to release it.
 cdm::FileIO* CdmAdapter::CreateFileIO(cdm::FileIOClient* client) {
-  return new CdmFileIOImpl(client, pp_instance());
+  return new CdmFileIOImpl(
+      client,
+      pp_instance(),
+      callback_factory_.NewCallback(&CdmAdapter::OnFirstFileRead));
 }
 
 #if defined(OS_CHROMEOS)

media/cdm/ppapi/cdm_adapter.h

@@ -247,6 +247,9 @@ class CdmAdapter : public pp::Instance,
 
   bool IsValidVideoFrame(const LinkedVideoFrame& video_frame);
 
+  // Callback to report |file_size_bytes| of the first file read by FileIO.
+  void OnFirstFileRead(int32_t file_size_bytes);
+
 #if !defined(NDEBUG)
   // Logs the given message to the JavaScript console associated with the
   // CDM adapter instance. The name of the CDM adapter issuing the log message
@@ -298,6 +301,9 @@ class CdmAdapter : public pp::Instance,
   bool deferred_initialize_video_decoder_;
   uint32_t deferred_video_decoder_config_id_;
 
+  uint32_t last_read_file_size_kb_;
+  bool file_size_uma_reported_;
+
   DISALLOW_COPY_AND_ASSIGN(CdmAdapter);
 };
 

media/cdm/ppapi/cdm_file_io_impl.cc

@@ -55,12 +55,17 @@ CdmFileIOImpl::ResourceTracker::~ResourceTracker() {
   delete CdmFileIOImpl::file_lock_map_;
 }
 
-CdmFileIOImpl::CdmFileIOImpl(cdm::FileIOClient* client, PP_Instance pp_instance)
+CdmFileIOImpl::CdmFileIOImpl(
+    cdm::FileIOClient* client,
+    PP_Instance pp_instance,
+    const pp::CompletionCallback& first_file_read_cb)
     : state_(FILE_UNOPENED),
       client_(client),
       pp_instance_handle_(pp_instance),
       callback_factory_(this),
-      io_offset_(0) {
+      io_offset_(0),
+      first_file_read_reported_(false),
+      first_file_read_cb_(first_file_read_cb) {
   PP_DCHECK(IsMainThread());
   PP_DCHECK(pp_instance);  // 0 indicates a "NULL handle".
 }
@@ -336,6 +341,14 @@ void CdmFileIOImpl::OnFileRead(int32_t bytes_read) {
   state_ = FILE_OPENED;
   const uint8_t* data = local_buffer.empty() ?
       NULL : reinterpret_cast<const uint8_t*>(&local_buffer[0]);
+
+  // Call this before OnReadComplete() so that we always have the latest file
+  // size before CDM fires errors.
+  if (!first_file_read_reported_) {
+    first_file_read_cb_.Run(local_buffer.size());
+    first_file_read_reported_ = true;
+  }
+
   client_->OnReadComplete(
       cdm::FileIOClient::kSuccess, data, local_buffer.size());
 }

media/cdm/ppapi/cdm_file_io_impl.h

@@ -35,7 +35,12 @@ class CdmFileIOImpl : public cdm::FileIO {
     DISALLOW_COPY_AND_ASSIGN(ResourceTracker);
   };
 
-  CdmFileIOImpl(cdm::FileIOClient* client, PP_Instance pp_instance);
+  // After the first successful file read, call |first_file_read_cb| to report
+  // the file size. |first_file_read_cb| takes one parameter: the file size in
+  // bytes.
+  CdmFileIOImpl(cdm::FileIOClient* client,
+                PP_Instance pp_instance,
+                const pp::CompletionCallback& first_file_read_cb);
 
   // cdm::FileIO implementation.
   virtual void Open(const char* file_name, uint32_t file_name_size) OVERRIDE;
@@ -158,6 +163,11 @@ class CdmFileIOImpl : public cdm::FileIO {
   // when read completes.
   std::vector<char> cumulative_read_buffer_;
 
+  bool first_file_read_reported_;
+
+  // Callback to report the file size in bytes after the first successful read.
+  pp::CompletionCallback first_file_read_cb_;
+
   DISALLOW_COPY_AND_ASSIGN(CdmFileIOImpl);
 };
 

tools/metrics/histograms/histograms.xml

@@ -11228,6 +11228,23 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <summary>Duration in milliseconds of HTML5 media (when known).</summary>
 </histogram>
 
+<histogram name="Media.EME.CdmFileIO.FileSizeKBOnError" units="KB">
+  <owner>xhwang@chromium.org</owner>
+  <summary>
+    Size in KB of the last file sucessfully read by the CDM through CDM FileIO
+    before a specific error happens. This is reported only when the error
+    happens, which should be rare.
+  </summary>
+</histogram>
+
+<histogram name="Media.EME.CdmFileIO.FileSizeKBOnFirstRead" units="KB">
+  <owner>xhwang@chromium.org</owner>
+  <summary>
+    Size in KB of the first file sucessfully read by the CDM through CDM FileIO.
+    This is recorded once per CDM instance.
+  </summary>
+</histogram>
+
 <histogram name="Media.EME.ClearKey.addKey" enum="MediaKeyException">
   <owner>xhwang@chromium.org</owner>
   <summary>addKey result using the Clear Key key system.</summary>