Blink side of changes to enable cache clearing without a flag.

Source/platform/graphics/ContentLayerDelegate.cpp

Index: Source/platform/graphics/ContentLayerDelegate.cpp
diff --git a/Source/platform/graphics/ContentLayerDelegate.cpp b/Source/platform/graphics/ContentLayerDelegate.cpp
index 1e63650c8de1ec49a293119d8e3f3aa4e7f1a3ab..3a38de713911d970403a3c669ae77aab661cfbf3 100644
--- a/Source/platform/graphics/ContentLayerDelegate.cpp
+++ b/Source/platform/graphics/ContentLayerDelegate.cpp
@@ -72,12 +72,15 @@ void ContentLayerDelegate::paintContents(
 
 void ContentLayerDelegate::paintContents(
     WebDisplayItemList* webDisplayItemList, const WebRect& clip,
-    WebContentLayerClient::GraphicsContextStatus contextStatus)
+    const bool clearCaches, WebContentLayerClient::GraphicsContextStatus contextStatus)
 {
     // Once Slimming Paint is fully implemented, this method will no longer
     // be needed since Blink will be in charge of creating the display list
     // during the document lifecylcle.
 
+    if (clearCaches)
+        m_painter->displayItemList()->invalidateAll();
+
     // Some layers don't yet produce display lists. To handle such layers, we
     // create a canvas backed by an SkPicture, and manually insert this
     // SkPicture into the WebDisplayItemList when the layer's display list is