Implement ConstraintNotSatisfiedError for getusermedia

content/renderer/media/media_stream_video_source.cc

Index: content/renderer/media/media_stream_video_source.cc
diff --git a/content/renderer/media/media_stream_video_source.cc b/content/renderer/media/media_stream_video_source.cc
index 42c5b1b4c558aeb7bfcd849c274e95f79d7960a5..2b19bcba15c56ecbdba7d8f96c19c7e7e3d0203a 100644
--- a/content/renderer/media/media_stream_video_source.cc
+++ b/content/renderer/media/media_stream_video_source.cc
@@ -220,7 +220,8 @@ void FilterFormatsByConstraint(
 // Returns the media::VideoCaptureFormats that matches |constraints|.
 media::VideoCaptureFormats FilterFormats(
     const blink::WebMediaConstraints& constraints,
-    const media::VideoCaptureFormats& supported_formats) {
+    const media::VideoCaptureFormats& supported_formats,
+    blink::WebString* unsatisfied_constraint) {
   if (constraints.isNull()) {
     return supported_formats;
   }
@@ -270,11 +271,15 @@ media::VideoCaptureFormats FilterFormats(
   constraints.getMandatoryConstraints(mandatory);
   constraints.getOptionalConstraints(optional);
   media::VideoCaptureFormats candidates = supported_formats;
-  for (size_t i = 0; i < mandatory.size(); ++i)
+  for (size_t i = 0; i < mandatory.size(); ++i) {
     FilterFormatsByConstraint(mandatory[i], true, &candidates);
-
-  if (candidates.empty())
-    return candidates;
+    // Here we record the name of constraint that causes

[miu, 2014/07/30 19:37:23]

This comment is stating the obvious, so you should just get rid of it.

[jiajia.qin, 2014/07/31 13:43:01]

Done.

+    // the ConstraintNotSatisfiedError
+    if (candidates.empty()) {
+      *unsatisfied_constraint = mandatory[i].m_name;
+      return candidates;

[miu, 2014/07/30 19:37:23]

Sanity-check: With this change, you're now aborting the loop early on the first
constraint that eliminates all candidates.  Before, the code would loop through
all constraints unconditionally.  Are you sure there aren't any INTENDED side
effects that you've eliminated with this behavior change?

[jiajia.qin, 2014/07/31 13:43:01]

Yes, I am sure. According to the spec, 'ConstraintNotSatisfiedError: One of the
mandatory constraints could not be satisfied' says if one of mandatory
constraints is not satisfied, ConstraintNotSatisfiedError will be thrown.

+    }
+  }
 
   // Ok - all mandatory checked and we still have candidates.
   // Let's try filtering using the optional constraints. The optional
@@ -405,7 +410,7 @@ void MediaStreamVideoSource::AddTrack(
     case ENDED:
     case STARTED: {
       // Currently, reconfiguring the source is not supported.
-      FinalizeAddTrack();
+      FinalizeAddTrack(MEDIA_DEVICE_OK);
     }
   }
 }
@@ -462,7 +467,7 @@ void MediaStreamVideoSource::OnSupportedFormats(
     SetReadyState(blink::WebMediaStreamSource::ReadyStateEnded);
     // This object can be deleted after calling FinalizeAddTrack. See comment
     // in the header file.
-    FinalizeAddTrack();
+    FinalizeAddTrack(MEDIA_DEVICE_CONSTRAINT_NOT_SATISFIED);

[miu, 2014/07/30 19:37:23]

re: My comment in the .h file:

The call to FindBestFormatWithConstraints() (a few lines above) should have an
unsatisfied_constraint string output argument, and then you can pass it to
FinalizeAddTrack() here.

[jiajia.qin, 2014/07/31 13:43:01]

Done.

     return;
   }
 
@@ -501,7 +506,7 @@ bool MediaStreamVideoSource::FindBestFormatWithConstraints(
       return true;
     }
     media::VideoCaptureFormats filtered_formats =
-        FilterFormats(requested_constraints, formats);
+        FilterFormats(requested_constraints, formats, &unsatisfied_constraint_);
     if (filtered_formats.size() > 0) {
       // A request with constraints that can be fulfilled.
       GetBestCaptureFormat(filtered_formats,
@@ -513,10 +518,10 @@ bool MediaStreamVideoSource::FindBestFormatWithConstraints(
   return false;
 }
 
-void MediaStreamVideoSource::OnStartDone(bool success) {
+void MediaStreamVideoSource::OnStartDone(MediaStreamRequestResult result) {
   DCHECK(CalledOnValidThread());
-  DVLOG(3) << "OnStartDone({success =" << success << "})";
-  if (success) {
+  DVLOG(3) << "OnStartDone({result =" << result << "})";
+  if (result == MEDIA_DEVICE_OK) {
     DCHECK_EQ(STARTING, state_);
     state_ = STARTED;
     SetReadyState(blink::WebMediaStreamSource::ReadyStateLive);
@@ -526,10 +531,10 @@ void MediaStreamVideoSource::OnStartDone(bool success) {
 
   // This object can be deleted after calling FinalizeAddTrack. See comment in
   // the header file.
-  FinalizeAddTrack();
+  FinalizeAddTrack(result);
 }
 
-void MediaStreamVideoSource::FinalizeAddTrack() {
+void MediaStreamVideoSource::FinalizeAddTrack(MediaStreamRequestResult result) {
   DCHECK(CalledOnValidThread());
   media::VideoCaptureFormats formats;
   formats.push_back(current_format_);
@@ -538,17 +543,7 @@ void MediaStreamVideoSource::FinalizeAddTrack() {
   callbacks.swap(requested_constraints_);
   for (std::vector<RequestedConstraints>::iterator it = callbacks.begin();
        it != callbacks.end(); ++it) {
-    // The track has been added successfully if the source has started and
-    // there are either no mandatory constraints and the source doesn't expose
-    // its format capabilities, or the constraints and the format match.
-    // For example, a remote source doesn't expose its format capabilities.
-    bool success =
-        state_ == STARTED &&
-        ((!current_format_.IsValid() && !HasMandatoryConstraints(
-            it->constraints)) ||
-         !FilterFormats(it->constraints, formats).empty());
-
-    if (success) {
+    if (result == MEDIA_DEVICE_OK) {
       int max_width;
       int max_height;
       GetDesiredMaxWidthAndHeight(it->constraints, &max_width, &max_height);
@@ -572,10 +567,10 @@ void MediaStreamVideoSource::FinalizeAddTrack() {
                                on_mute_callback);
     }
 
-    DVLOG(3) << "FinalizeAddTrack() success " << success;
+    DVLOG(3) << "FinalizeAddTrack() result " << result;
 
     if (!it->callback.is_null())
-      it->callback.Run(this, success);
+      it->callback.Run(this, result, unsatisfied_constraint_);
   }
 }