[DevTools] Use device metrics emulation implemented in content.

public/web/WebView.h

 /*
  * Copyright (C) 2009, 2010, 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
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@@ skipping 382 matching lines @@
     // point.
     virtual void inspectElementAt(const WebPoint&) = 0;
 
     // Settings used by the inspector.
     virtual WebString inspectorSettings() const = 0;
     virtual void setInspectorSettings(const WebString&) = 0;
     virtual bool inspectorSetting(const WebString& key,
                                   WebString* value) const = 0;
     virtual void setInspectorSetting(const WebString& key,
                                      const WebString& value) = 0;
+    virtual void setDeviceEmulationParameters(

[aelias_OOO_until_Jul13, 2013/10/01 08:08:51]

You're introducing a second Blink API to bounce back some information that Blink
could've computed in the first place.  Let's avoid this criss-crossing
dependency.

The new information you're getting back through here is the rootLayerScale which
is calculated by fit_to_view.  But you have enough information to do the
fit_to_view calculation on the Blink side.  Please move that calculation to
Blink and then tell both RenderView and WebViewImpl about the scale you
calculated, and delete this WebView.h change.

[aelias_OOO_until_Jul13, 2013/10/01 08:24:22]

As discussed offline, it can't be eliminated, so let's just split into two
narrowly named methods for clarity:

setCompositorDeviceScaleFactorOverride()
setRootLayerScaleTransform()

[dgozman, 2013/10/01 15:26:34]

Done.

+        bool enabled,
+        float deviceScaleFactor,
+        float rootLayerScale) = 0;
 
     // The embedder may optionally engage a WebDevToolsAgent.  This may only
     // be set once per WebView.
     virtual WebDevToolsAgent* devToolsAgent() = 0;
 
 
     // Accessibility -------------------------------------------------------
 
     // Returns the accessibility object for this view.
     virtual WebAXObject accessibilityObject() = 0;
@@ skipping 105 matching lines @@
 
     // Testing functionality for TestRunner ---------------------------------
 
 protected:
     ~WebView() {}
 };
 
 } // namespace WebKit
 
 #endif