Change DebugCanvas API to not encourage memory leaks

debugger/SkDebugger.h

Index: debugger/SkDebugger.h
diff --git a/debugger/SkDebugger.h b/debugger/SkDebugger.h
index 5359b10fe96bbdc57ffb8d1fc6c5d806bff8033e..052d6fe621571a8bffed8d75bf55ceff0070e805 100644
--- a/debugger/SkDebugger.h
+++ b/debugger/SkDebugger.h
@@ -44,12 +44,12 @@ public:
         fDebugCanvas->toggleCommand(index, isVisible);
     }
 
-    SkTArray<SkString>* getDrawCommandsAsStrings() {
-        return fDebugCanvas->getDrawCommandsAsStrings();
+    void getDrawCommandsAsStrings(SkTArray<SkString>* outCommandStrings) {
+        fDebugCanvas->getDrawCommandsAsStrings(outCommandStrings);
     }
 
-    SkTDArray<size_t>* getDrawCommandOffsets() {
-        return fDebugCanvas->getDrawCommandOffsets();
+    void getDrawCommandOffsets(SkTDArray<size_t>* outCommandOffsets) {
+        fDebugCanvas->getDrawCommandOffsets(outCommandOffsets);
     }
 
     const SkTDArray<SkDrawCommand*>& getDrawCommands() const {