Image Capture: two small nits

Android Auto Exposure is always available, make the implementation
reflect that.

In blink, don't fill dictionary entries with empty arrays.

BUG=716636

Review-Url: https://codereview.chromium.org/2842103002
Cr-Commit-Position: refs/heads/master@{#468205}

media/capture/video/android/java/src/org/chromium/media/VideoCaptureCamera.java

@@ -533,13 +533,10 @@ public class VideoCaptureCamera
         }
         builder.setFocusMode(jniFocusMode);
 
-        // Auto Exposure is the usual capability and state, unless AE is not available at all, which
-        // is signalled by the absence of Metering Areas. Exposure Compensation can also support or
-        // be locked, this is equivalent to AndroidMeteringMode.FIXED.
+        // Auto Exposure is understood to be supported always; besides that, only "locked"
+        // (equivalent to AndroidMeteringMode.FIXED) may be supported and/or configured.
         ArrayList<Integer> jniExposureModes = new ArrayList<Integer>(2);
-        if (parameters.getMaxNumMeteringAreas() > 0) {
         jniExposureModes.add(AndroidMeteringMode.CONTINUOUS);
-        }
         if (parameters.isAutoExposureLockSupported()) {
             jniExposureModes.add(AndroidMeteringMode.FIXED);
         }

third_party/WebKit/Source/modules/imagecapture/ImageCapture.cpp

@@ -403,7 +403,7 @@ void ImageCapture::ClearMediaTrackConstraints(ScriptPromiseResolver* resolver) {
 }
 
 void ImageCapture::GetMediaTrackSettings(MediaTrackSettings& settings) const {
-  // Merge any present |m_settings| members into |settings|.
+  // Merge any present |settings_| members into |settings|.
 
   if (settings_.hasWhiteBalanceMode())
     settings.setWhiteBalanceMode(settings_.whiteBalanceMode());
@@ -412,8 +412,10 @@ void ImageCapture::GetMediaTrackSettings(MediaTrackSettings& settings) const {
   if (settings_.hasFocusMode())
     settings.setFocusMode(settings_.focusMode());
 
-  if (settings_.hasPointsOfInterest())
+  if (settings_.hasPointsOfInterest() &&
+      !settings_.pointsOfInterest().IsEmpty()) {
     settings.setPointsOfInterest(settings_.pointsOfInterest());
+  }
 
   if (settings_.hasExposureCompensation())
     settings.setExposureCompensation(settings_.exposureCompensation());
@@ -504,6 +506,8 @@ void ImageCapture::OnPhotoCapabilities(
       caps->SetImageWidth(
           MediaSettingsRange::Create(std::move(capabilities->width)));
     }
+
+    if (!capabilities->fill_light_mode.IsEmpty())
       caps->SetFillLightMode(capabilities->fill_light_mode);
 
     resolver->Resolve(caps);