Android's Smart Select uses the text surrounding a selection to potentially suggest a larger selection. Currently we get the surrounding text by making a round trip to the renderer with SmartSelectionClient.requestSurroundingText() and SmartSelectionClient.onSurroundingTextReceived(). We can avoid this round trip by having the renderer send the surrounding text to the browser in the ContextMenuParams. Then we pass the surrounding text to SelectionPopupController.showSelectionMenu().