Begin migrating the vm service from a rest-style interface to a json-rpc style interface.

runtime/observatory/lib/src/elements/cpu_profile.dart

Index: runtime/observatory/lib/src/elements/cpu_profile.dart
diff --git a/runtime/observatory/lib/src/elements/cpu_profile.dart b/runtime/observatory/lib/src/elements/cpu_profile.dart
index 44b9e0baffffe67c5b24670a1172a5504f1ad142..154f80fee98b6c44be366ac5369b42f60c81f37c 100644
--- a/runtime/observatory/lib/src/elements/cpu_profile.dart
+++ b/runtime/observatory/lib/src/elements/cpu_profile.dart
@@ -140,7 +140,9 @@ class ProfileCodeTrieNodeTreeRow extends TableTreeRow {
 @CustomTag('cpu-profile')
 class CpuProfileElement extends ObservatoryElement {
   CpuProfileElement.created() : super.created();
-  @published ServiceMap profile;
+  @published Isolate isolate;
+
+  @observable ServiceMap profile;
   @observable bool hideTagsChecked;
   @observable String sampleCount = '';
   @observable String refreshTime = '';
@@ -150,32 +152,28 @@ class CpuProfileElement extends ObservatoryElement {
   @observable String timeSpan = '';
   @reflectable double displayThreshold = 0.0002; // 0.02%.
 
-  @observable String tagSelector = 'uv';
+  @observable String tagSelector = 'UserVM';
 
   final _id = '#tableTree';
   TableTree tree;
 
   static const MICROSECONDS_PER_SECOND = 1000000.0;
 
-  void profileChanged(oldValue) {
-    if (profile == null) {
+  void isolateChanged(oldValue) {
+    if (isolate == null) {
+      profile = null;
       return;
     }
-    var totalSamples = profile['samples'];
-    var now = new DateTime.now();
-    sampleCount = totalSamples.toString();
-    refreshTime = now.toString();
-    sampleDepth = profile['depth'].toString();
-    var period = profile['period'];
-    sampleRate = (MICROSECONDS_PER_SECOND / period).toStringAsFixed(0);
-    timeSpan = formatTime(profile['timeSpan']);
-    displayCutoff = '${(displayThreshold * 100.0).toString()}%';
-    profile.isolate.processProfile(profile);
-    profile['threshold'] = displayThreshold;
-    _update();
+    isolate.invokeRpc('getCpuProfile', { 'tags': tagSelector })
+      .then((ServiceObject obj) {
+          print(obj);
+          // Assert we got back the a profile.
+          assert(obj.type == 'CpuProfile');
+          profile = obj;
+          _update();
+      });
   }
 
-
   @override
   void attached() {
     super.attached();
@@ -186,22 +184,34 @@ class CpuProfileElement extends ObservatoryElement {
   }
 
   void tagSelectorChanged(oldValue) {
-    refresh(null);
+    isolateChanged(null);
   }
 
   void refresh(var done) {
-    var request = 'profile?tags=$tagSelector';
-    profile.isolate.get(request).then((ServiceMap m) {
-      // Assert we got back the a profile.
-      assert(m.type == 'Profile');
-      profile = m;
-    }).whenComplete(done);
+    isolate.invokeRpc('getCpuProfile', { 'tags': tagSelector })
+      .then((ServiceObject obj) {
+          // Assert we got back the a profile.
+          assert(obj.type == 'CpuProfile');
+          profile = obj;
+          _update();
+      }).whenComplete(done);
   }
 
   void _update() {
     if (profile == null) {
       return;
     }
+    var totalSamples = profile['samples'];
+    var now = new DateTime.now();
+    sampleCount = totalSamples.toString();
+    refreshTime = now.toString();
+    sampleDepth = profile['depth'].toString();
+    var period = profile['period'];
+    sampleRate = (MICROSECONDS_PER_SECOND / period).toStringAsFixed(0);
+    timeSpan = formatTime(profile['timeSpan']);
+    displayCutoff = '${(displayThreshold * 100.0).toString()}%';
+    profile.isolate.processProfile(profile);
+    profile['threshold'] = displayThreshold;
     _buildTree();
   }