Change DebugCanvas API to not encourage memory leaks

src/utils/debugger/SkDebugCanvas.h

Index: src/utils/debugger/SkDebugCanvas.h
diff --git a/src/utils/debugger/SkDebugCanvas.h b/src/utils/debugger/SkDebugCanvas.h
index 18f4c8d71336a4c22f648f13e546fe3bad66d07e..b064389fb5c0e8108f53c38f33fd9bad9c0f96c8 100644
--- a/src/utils/debugger/SkDebugCanvas.h
+++ b/src/utils/debugger/SkDebugCanvas.h
@@ -123,14 +123,14 @@ public:
     SkTDArray<SkDrawCommand*>& getDrawCommands();
 
     /**
-     * Returns the string vector of draw commands
+     * Fills the string vector with draw commands 
      */
-    SkTArray<SkString>* getDrawCommandsAsStrings() const;
+    void getDrawCommandsAsStrings(SkTArray<SkString>* outCommandStrings) const;
 
     /**
-     * Returns an array containing an offset (in the SkPicture) for each command
+     * Fills the size_t array with an offset (in the SkPicture) for each command
      */
-    SkTDArray<size_t>* getDrawCommandOffsets() const;
+    void getDrawCommandOffsets(SkTDArray<size_t>* outCommandOffsets) const;
 
     /**
         Returns length of draw command vector.