Adds scroll position/scale emulation to DevTools.

third_party/WebKit/Source/web/DevToolsEmulator.cpp

Index: third_party/WebKit/Source/web/DevToolsEmulator.cpp
diff --git a/third_party/WebKit/Source/web/DevToolsEmulator.cpp b/third_party/WebKit/Source/web/DevToolsEmulator.cpp
index 848f4e121489e3eb3daee48891475e134128abbc..3f8202d546f48667ed092084bfb0bb77e93b61be 100644
--- a/third_party/WebKit/Source/web/DevToolsEmulator.cpp
+++ b/third_party/WebKit/Source/web/DevToolsEmulator.cpp
@@ -223,6 +223,7 @@ void DevToolsEmulator::enableDeviceEmulation(const WebDeviceEmulationParams& par
     // TODO(dgozman): mainFrameImpl() is null when it's remote. Figure out how
     // we end up with enabling emulation in this case.
     if (m_webViewImpl->mainFrameImpl()) {
+        m_webViewImpl->mainFrameImpl()->frameView()->layout();
         if (Document* document = m_webViewImpl->mainFrameImpl()->frame()->document())
             document->mediaQueryAffectingValueChanged();
     }
@@ -239,9 +240,10 @@ void DevToolsEmulator::disableDeviceEmulation()
     disableMobileEmulation();
     m_webViewImpl->setCompositorDeviceScaleFactorOverride(0.f);
     m_webViewImpl->setRootLayerTransform(WebSize(0.f, 0.f), 1.f);
-    m_webViewImpl->setPageScaleFactor(1.f);
+    m_webViewImpl->resetScaleStateImmediately();
     // mainFrameImpl() could be null during cleanup or remote <-> local swap.
     if (m_webViewImpl->mainFrameImpl()) {
+        m_webViewImpl->mainFrameImpl()->frameView()->layout();
         if (Document* document = m_webViewImpl->mainFrameImpl()->frame()->document())
             document->mediaQueryAffectingValueChanged();
     }
@@ -282,10 +284,6 @@ void DevToolsEmulator::enableMobileEmulation()
     m_originalDefaultMinimumPageScaleFactor = m_webViewImpl->defaultMinimumPageScaleFactor();
     m_originalDefaultMaximumPageScaleFactor = m_webViewImpl->defaultMaximumPageScaleFactor();
     m_webViewImpl->setDefaultPageScaleLimits(0.25f, 5);
-    // TODO(dgozman): mainFrameImpl() is null when it's remote. Figure out how
-    // we end up with enabling emulation in this case.
-    if (m_webViewImpl->mainFrameImpl())
-        m_webViewImpl->mainFrameImpl()->frameView()->layout();
 }
 
 void DevToolsEmulator::disableMobileEmulation()
@@ -314,9 +312,6 @@ void DevToolsEmulator::disableMobileEmulation()
     m_webViewImpl->setDefaultPageScaleLimits(
         m_originalDefaultMinimumPageScaleFactor,
         m_originalDefaultMaximumPageScaleFactor);
-    // mainFrameImpl() could be null during cleanup or remote <-> local swap.
-    if (m_webViewImpl->mainFrameImpl())
-        m_webViewImpl->mainFrameImpl()->frameView()->layout();
 }
 
 void DevToolsEmulator::setTouchEventEmulationEnabled(bool enabled)