Bug 1865995 p5. Rename GetContentViewerSize to match nsIDocumentViewer's new name. r=emilio,geckoview-reviewers,owlish

Includes the methods on:
 - nsIDOMWindowUtils
 - nsLayoutUtils
 - MVMContext

Differential Revision: https://phabricator.services.mozilla.com/D194339

layout/base/PresShell.cpp

@@ -11449,7 +11449,7 @@ bool PresShell::DetermineFontSizeInflationState() {
     nsPresContext* topContext =
         mPresContext->GetInProcessRootContentDocumentPresContext();
     LayoutDeviceIntSize result;
-    if (!nsLayoutUtils::GetContentViewerSize(topContext, result)) {
+    if (!nsLayoutUtils::GetDocumentViewerSize(topContext, result)) {
       return false;
     }
     displaySize = Some(result);