Reland: Make 2D canvas disable gpu acceleration when getImageData is called

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
index bfd4ac0787e2ea883278e4d58ee0d8d7ac8ddab9..968d1f06022216cc6a3ffbeb13c212c5bddb39e5 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -318,6 +318,13 @@ void HTMLCanvasElement::didFinalizeFrame()
     m_dirtyRect = FloatRect();
 }
 
+void HTMLCanvasElement::didDisableAcceleration()
+{
+    // We must force a paint invalidation on the canvas even if it's
+    // content did not change because it layer was destroyed.
+    didDraw(FloatRect(0, 0, size().width(), size().height()));
+}
+
 void HTMLCanvasElement::restoreCanvasMatrixClipStack(SkCanvas* canvas) const
 {
     if (m_context)