Make PageScaleFactor work for oopif subframes.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index cc597bd1005feb03373f86ae3d7fa3b5266b330f..61af2e1ebcf6cfd9ce902920f5a97a948a630db2 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -1241,6 +1241,8 @@ bool RenderViewImpl::OnMessageReceived(const IPC::Message& message) {
                         OnUpdateWindowScreenRect)
     IPC_MESSAGE_HANDLER(PageMsg_SetZoomLevel, OnSetZoomLevel)
     IPC_MESSAGE_HANDLER(PageMsg_SetDeviceScaleFactor, OnSetDeviceScaleFactor);
+  IPC_MESSAGE_HANDLER(PageMsg_SetPageScaleFactor,
+                      OnSetPageScaleFactorForSubframes);
     IPC_MESSAGE_HANDLER(PageMsg_WasHidden, OnPageWasHidden)
     IPC_MESSAGE_HANDLER(PageMsg_WasShown, OnPageWasShown)
     IPC_MESSAGE_HANDLER(PageMsg_SetHistoryOffsetAndLength,
@@ -2376,6 +2378,24 @@ void RenderViewImpl::OnDeviceScaleFactorChanged() {
     AutoResizeCompositor();
 }
 
+void RenderViewImpl::OnSetPageScaleFactorForSubframes(double page_scale) {
+  if (webview() && webview()->mainFrame() &&
+      !webview()->mainFrame()->isWebLocalFrame()) {

[kenrb, 2017/01/24 17:13:27]

It's cleaner to test the inverted conditions, and return early if they aren't
met.

[wjmaclean, 2017/01/24 18:24:26]

Done.

+    // TODO(wjmaclean): Find a better way to identify the local roots in the
+    // frame tree. Still, this is likely better than sending a separate IPC for
+    // every frame in a renderer.

[kenrb, 2017/01/24 17:13:27]

That is technically true, but an alternative is to send a message individually
just to local frame roots. WebContentsImpl::GetRenderWidgetHostViewsInTree()
facilitates doing that. That is likely a better approach since there is no state
getting attached to a page-level object in the renderer.

[wjmaclean, 2017/01/24 18:24:26]

Ok, I didn't know about that ... I'll look into that. Would this handler move to
RenderWidget in that case? I'm guessing 'yes' ...

[kenrb, 2017/01/24 18:47:30]

Yes. Hypothetically it could go on RenderFrameImpl but RenderWidget makes more
sense.

+    for (WebFrame* frame = webview()->mainFrame(); frame;
+         frame = frame->traverseNext()) {
+      if (frame->isWebLocalFrame() && !frame->parent()->isWebLocalFrame()) {
+        RenderFrameImpl* rfi = RenderFrameImpl::FromWebFrame(frame);
+        RenderWidgetCompositor* widget_compositor =
+            rfi->GetRenderWidget()->compositor();
+        widget_compositor->SetPageScaleFactorForSubframe(page_scale);
+      }
+    }
+  }
+}
+
 void RenderViewImpl::SetScreenMetricsEmulationParameters(
     bool enabled,
     const blink::WebDeviceEmulationParams& params) {