Translate viewport related meta tags into @viewport descriptors as suggested by the CSS Device Adap…

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 4f23298076d330f7892464fa0870eb8c8e04ed2f..446a4a9b8e4eb219c2e32ba2e9575129d59d77a8 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -87,6 +87,7 @@
 #include "WebTextInputInfo.h"
 #include "WebViewClient.h"
 #include "core/accessibility/AXObjectCache.h"
+#include "core/css/StyleSheetContents.h"
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentMarkerController.h"
@@ -2967,6 +2968,38 @@ void WebViewImpl::setUserAgentPageScaleConstraints(PageScaleConstraints newConst
         return;
 
     m_pageScaleConstraintsSet.setUserAgentConstraints(newConstraints);
+    m_pageScaleConstraintsSet.setNeedsReset(true);
+
+    Vector<String> whitelist;
+    Document* document = m_page->mainFrame()->document();
+    whitelist.append(document->url());
+
+    StringBuilder builder;
+
+    builder.append("@viewport{");
+
+    if (newConstraints.initialScale > 0) {
+        builder.appendLiteral("zoom:");
+        builder.append(String::number(newConstraints.initialScale));
+        builder.appendLiteral("!important;");
+    }
+
+    if (newConstraints.minimumScale > 0) {
+        builder.appendLiteral("min-zoom:");
+        builder.append(String::number(newConstraints.minimumScale));
+        builder.appendLiteral("!important;");
+    }
+
+    if (newConstraints.maximumScale > 0) {
+        builder.appendLiteral("max-zoom:");
+        builder.append(String::number(newConstraints.maximumScale));
+        builder.appendLiteral("!important;");
+    }
+
+    builder.append("}");
+
+    removeAllUserContent();
+    addUserStyleSheet(builder.toString(), whitelist, UserContentInjectInAllFrames, UserStyleInjectInExistingDocuments);
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return;
@@ -2978,11 +3011,6 @@ void WebViewImpl::setInitialPageScaleOverride(float initialPageScaleFactorOverri
 {
     PageScaleConstraints constraints = m_pageScaleConstraintsSet.userAgentConstraints();
     constraints.initialScale = initialPageScaleFactorOverride;
-
-    if (constraints == m_pageScaleConstraintsSet.userAgentConstraints())
-        return;
-
-    m_pageScaleConstraintsSet.setNeedsReset(true);
     setUserAgentPageScaleConstraints(constraints);
 }
 
@@ -3043,7 +3071,7 @@ void WebViewImpl::updatePageDefinedPageScaleConstraints(const ViewportArguments&
     if (!settings()->viewportEnabled() || !isFixedLayoutModeEnabled() || !page() || !m_size.width || !m_size.height)
         return;
 
-    m_pageScaleConstraintsSet.updatePageDefinedConstraints(arguments, m_size, page()->settings()->layoutFallbackWidth());
+    m_pageScaleConstraintsSet.updatePageDefinedConstraints(arguments, m_size);
 
     if (settingsImpl()->supportDeprecatedTargetDensityDPI())
         m_pageScaleConstraintsSet.adjustPageDefinedConstraintsForAndroidWebView(arguments, m_size, page()->settings()->layoutFallbackWidth(), deviceScaleFactor(), page()->settings()->useWideViewport(), page()->settings()->loadWithOverviewMode());
@@ -4141,9 +4169,8 @@ void WebViewImpl::pointerLockMouseEvent(const WebInputEvent& event)
 
 bool WebViewImpl::shouldDisableDesktopWorkarounds()
 {
-    ViewportArguments arguments = mainFrameImpl()->frame()->document()->viewportArguments();
-    return arguments.width == ViewportArguments::ValueDeviceWidth || !arguments.userZoom
-        || (arguments.minZoom == arguments.maxZoom && arguments.minZoom != ViewportArguments::ValueAuto);
+    Document* document = mainFrameImpl()->frame()->document();
+    return document->styleResolver()->viewportStyleResolver()->shouldDisableDesktopWorkarounds();
 }
 
 } // namespace WebKit