Add "exact" constraint evaluation to video picker.

content/renderer/media/media_stream_constraints_util.cc

Index: content/renderer/media/media_stream_constraints_util.cc
diff --git a/content/renderer/media/media_stream_constraints_util.cc b/content/renderer/media/media_stream_constraints_util.cc
index d313f3b94247917806310927d7f0499a5c0d2e7c..3150c94c547d767f3d137758dba962bc0bf73c36 100644
--- a/content/renderer/media/media_stream_constraints_util.cc
+++ b/content/renderer/media/media_stream_constraints_util.cc
@@ -41,12 +41,20 @@ bool ScanConstraintsForMaxValue(const blink::WebMediaConstraints& constraints,
     *value = the_field.max();
     return true;
   }
+  if (the_field.hasExact()) {
+    *value = the_field.exact();
+    return true;
+  }
   for (const auto& advanced_constraint : constraints.advanced()) {
     const auto& the_field = advanced_constraint.*picker;
     if (the_field.hasMax()) {
       *value = the_field.max();
       return true;
     }
+    if (the_field.hasExact()) {
+      *value = the_field.exact();
+      return true;
+    }
   }
   return false;
 }
@@ -60,12 +68,20 @@ bool ScanConstraintsForMinValue(const blink::WebMediaConstraints& constraints,
     *value = the_field.min();
     return true;
   }
+  if (the_field.hasExact()) {
+    *value = the_field.exact();
+    return true;
+  }
   for (const auto& advanced_constraint : constraints.advanced()) {
     const auto& the_field = advanced_constraint.*picker;
     if (the_field.hasMin()) {
       *value = the_field.min();
       return true;
     }
+    if (the_field.hasExact()) {
+      *value = the_field.exact();
+      return true;
+    }
   }
   return false;
 }