Fix leak in debug mirror cache.

src/debug-debugger.js

Index: src/debug-debugger.js
diff --git a/src/debug-debugger.js b/src/debug-debugger.js
index 660ea790389ae4e828681fe786683ee0f3a7a3a4..5462b53b6b0ba823218e144663bebcebff06facd 100644
--- a/src/debug-debugger.js
+++ b/src/debug-debugger.js
@@ -486,6 +486,12 @@ function GetScriptBreakPoints(script) {
 }
 
 
+function GetLoadedScripts() {
+  ClearMirrorCache();  // The mirror cache may be holding onto scripts.
+  return %DebugGetLoadedScripts();

[yurys, 2014/06/03 08:07:21]

This change looks wrong to me. By design of V8 debugging protocol mirror cache
should be kept while we are staying on a breakpoint so that the client could
access corresponding object by its mirror id. After this change, however, the
cache will be cleared on any call to GetLoadedScripts() and the remote id will
become invalid.

In case of blink the problem is that we create mirror objects not only when we
stay on a breakpoint and I'm not sure we clear them properly. Also we don't use
id->mirror map in blink and I believe a right way to fix this would be to
disable mirror cache in blink completely. WDYT?

[Yang, 2014/06/03 08:12:46]

Not sure I understand. Which code path does blink use to get loaded scripts?

+}
+
+
 Debug.setListener = function(listener, opt_data) {
   if (!IS_FUNCTION(listener) && !IS_UNDEFINED(listener) && !IS_NULL(listener)) {
     throw new Error('Parameters have wrong types.');
@@ -915,7 +921,7 @@ Debug.showBreakPoints = function(f, full, opt_position_alignment) {
 // scanning the heap.
 Debug.scripts = function() {
   // Collect all scripts in the heap.
-  return %DebugGetLoadedScripts();
+  return GetLoadedScripts();
 };
 
 
@@ -2244,7 +2250,7 @@ DebugCommandProcessor.prototype.scriptsRequest_ = function(request, response) {
   }
 
   // Collect all scripts in the heap.
-  var scripts = %DebugGetLoadedScripts();
+  var scripts = GetLoadedScripts();
 
   response.body = [];
 
@@ -2316,7 +2322,7 @@ DebugCommandProcessor.prototype.changeLiveRequest_ = function(
   var script_id = request.arguments.script_id;
   var preview_only = !!request.arguments.preview_only;
 
-  var scripts = %DebugGetLoadedScripts();
+  var scripts = GetLoadedScripts();
 
   var the_script = null;
   for (var i = 0; i < scripts.length; i++) {