DevTools: Add snapshot command log on the frontend.

Source/platform/graphics/GraphicsContextRecorder.cpp

Index: Source/platform/graphics/GraphicsContextRecorder.cpp
diff --git a/Source/platform/graphics/GraphicsContextRecorder.cpp b/Source/platform/graphics/GraphicsContextRecorder.cpp
index 02615de435184b81902e47fee8b0ae3087c9a66d..86d11ccaa34916baa927e96142545992afce73a7 100644
--- a/Source/platform/graphics/GraphicsContextRecorder.cpp
+++ b/Source/platform/graphics/GraphicsContextRecorder.cpp
@@ -164,22 +164,14 @@ private:
     Vector<double>* m_currentTimings;
 };
 
-class LoggingSnapshotPlayer : public SnapshotPlayer {
+class LoggingCanvas : public SkCanvas {
 public:
-    LoggingSnapshotPlayer(PassRefPtr<SkPicture> picture, SkCanvas* canvas)
-        : SnapshotPlayer(picture, canvas)
+    LoggingCanvas(int width, int height) : SkCanvas(width, height)
     {
+        initLog();
     }
 
-    virtual bool abortDrawing() OVERRIDE
-    {
-        return false;
-    }
-};
-
-class LoggingCanvas : public SkCanvas {
-public:
-    LoggingCanvas()
+    void initLog()
     {
         m_log = JSONArray::create();
     }
@@ -428,7 +420,8 @@ public:
     SaveLayerStrategy willSaveLayer(const SkRect* bounds, const SkPaint* paint, SaveFlags flags) OVERRIDE
     {
         RefPtr<JSONObject> params = addItemWithParams("saveLayer");
-        params->setObject("bounds", objectForSkRect(*bounds));
+        if (bounds)
+            params->setObject("bounds", objectForSkRect(*bounds));
         params->setObject("paint", objectForSkPaint(*paint));
         params->setString("saveFlags", saveFlagsToString(flags));
         this->SkCanvas::willSaveLayer(bounds, paint, flags);
@@ -988,6 +981,36 @@ private:
     }
 };
 
+class LoggingSnapshotPlayer : public SnapshotPlayer {
+public:
+    LoggingSnapshotPlayer(PassRefPtr<SkPicture> picture, LoggingCanvas* canvas)
+        : SnapshotPlayer(picture, canvas)
+    {
+    }
+
+    void play(unsigned fromStep, unsigned toStep)
+    {
+        m_fromStep = fromStep;
+        m_toStep = toStep;
+        m_stepCount = 0;
+        SnapshotPlayer::play();
+    }
+
+    virtual bool abortDrawing() OVERRIDE
+    {
+        ++m_stepCount;
+        if (m_stepCount == m_fromStep) {
+            static_cast<LoggingCanvas*>(canvas())->initLog();
+        }
+        return m_toStep && m_stepCount > m_toStep;
+    }
+
+private:
+    unsigned m_fromStep;
+    unsigned m_toStep;
+    unsigned m_stepCount;
+};
+
 static bool decodeBitmap(const void* data, size_t length, SkBitmap* result)
 {
     RefPtr<SharedBuffer> buffer = SharedBuffer::create(static_cast<const char*>(data), length);
@@ -1033,11 +1056,11 @@ PassOwnPtr<ImageBuffer> GraphicsContextSnapshot::createImageBuffer() const
     return ImageBuffer::create(IntSize(m_picture->width(), m_picture->height()), m_isCertainlyOpaque ? Opaque : NonOpaque);
 }
 
-PassRefPtr<JSONArray> GraphicsContextSnapshot::snapshotCommandLog() const
+PassRefPtr<JSONArray> GraphicsContextSnapshot::snapshotCommandLog(unsigned fromStep, unsigned toStep) const
 {
-    LoggingCanvas canvas;
-    FragmentSnapshotPlayer player(m_picture, &canvas);
-    player.play(0, 0);
+    LoggingCanvas canvas(m_picture->width(), m_picture->height());
+    LoggingSnapshotPlayer player(m_picture, &canvas);
+    player.play(fromStep, toStep);
     return canvas.log();
 }