blink: Enable the GPU trigger when viewport meta tag is not read

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 537ec2ece4d68f730694ef892c1ef33659abae53..147d0d166b747db3b3e97dc53ae7a3f6de2ca95d 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -3299,6 +3299,13 @@ void WebViewImpl::refreshPageScaleFactorAfterLayout()
 
 void WebViewImpl::updatePageDefinedViewportConstraints(const ViewportDescription& description)
 {
+    // If we're not reading the viewport meta tag, allow GPU rasterization.
+    if (!settingsImpl()->viewportMetaEnabled()) {
+        m_matchesHeuristicsForGpuRasterization = true;
+        if (m_layerTreeView)
+            m_layerTreeView->heuristicsForGpuRasterizationUpdated(m_matchesHeuristicsForGpuRasterization);
+    }
+
     if (!settings()->viewportEnabled() || !page() || (!m_size.width && !m_size.height) || !page()->mainFrame()->isLocalFrame())
         return;