Adds DevTools commands for forced viewport override.

third_party/WebKit/public/platform/WebLayerTreeView.h

Index: third_party/WebKit/public/platform/WebLayerTreeView.h
diff --git a/third_party/WebKit/public/platform/WebLayerTreeView.h b/third_party/WebKit/public/platform/WebLayerTreeView.h
index 48f41ae8b578cc28a5ad58c673cb227f46c5d00a..ac39059c688142f82f7129d026cc0455cac5ebc1 100644
--- a/third_party/WebKit/public/platform/WebLayerTreeView.h
+++ b/third_party/WebKit/public/platform/WebLayerTreeView.h
@@ -67,8 +67,10 @@ public:
     // View properties ---------------------------------------------------
 
     virtual void setViewportSize(const WebSize& deviceViewportSize) { }
+    virtual WebSize getViewportSize() const { return WebSize(); }

[chrishtr, 2016/08/22 22:00:42]

In what coordinate space? Not including the device scale factor?

[Eric Seckler, 2016/08/23 09:32:19]

It's in physical pixels. Added a comment.

 
     virtual void setDeviceScaleFactor(float) { }
+    virtual float getDeviceScaleFactor() const { return 1.f; }

[dgozman, 2016/08/22 22:22:06]

Having both set and get here looks strange. AFAIU, blink is supposed to control
WebLayerTreeView so it should already know the device scale factor it set.

[Eric Seckler, 2016/08/23 09:32:19]

True, except that there could be a device_scale_factor override in place within
Blink, which is why I query it from the layerTreeView/compositor. I got rid of
this and instead added a compositorDeviceScaleFactor() accessor to WebViewImpl
that returns |m_compositorDeviceScaleFactorOverride| if an override is active.
Is that more appropriate?

 
     // Sets the background color for the viewport.
     virtual void setBackgroundColor(WebColor) { }