Fix visual viewport for OOPIF.

content/browser/frame_host/render_widget_host_view_child_frame.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_widget_host_view_child_frame.h"
 
 #include <algorithm>
 #include <utility>
 #include <vector>
 
@@ skipping 103 matching lines @@
 
     // The parent_view can be null in tests when using a TestWebContents.
     if (parent_view) {
       // Translate frame_rect by the parent's RenderWidgetHostView offset.
       rect.Offset(parent_view->GetViewBounds().OffsetFromOrigin());
     }
   }
   return rect;
 }
 
+gfx::Size RenderWidgetHostViewChildFrame::GetVisibleViewportSize() const {
+  // For subframes, the visual viewport corresponds to the main frame size, so
+  // this bubbles up to the parent until it will hit the main frame's
+  // RenderWidgetHostView.
+  //
+  // Currently this excludes webview guests, since they expect the visual
+  // viewport to return the guest's size rather than the page's; one reason why
+  // is that Blink ends up using the visual viewport to calculate things like
+  // window.innerWidth/innerHeight for main frames, and a guest is considered
+  // to be a main frame.  This should be cleaned up eventually.

[alexmos, 2016/03/26 00:00:48]

I'm not quite sure about this, and in general about what visual viewport means
for guests, so it'd be great to double-check this comment/logic.  I added the
|is_guest| exclusion because of tests like
WebViewTest.Shim_TestNavigateAfterResize/0.  With
--use-cross-process-frames-for-guests, this would return incorrect
window.innerWidth/Height for guest (embedder's size rather than guest's size)
without that exception.

For reference, here's the code from getViewportSize in LocalDOMWindow.cpp, which
is what's used for innerWidth/innerHeight:

    return frame->isMainFrame() && !host->settings().inertVisualViewport()
        ? FloatSize(host->visualViewport().visibleRect().size())
        : FloatSize(view->visibleContentRect(IncludeScrollbars).size());

For OOP subframes, we take the second path.  For a guest, we take the first
path.

[kenrb, 2016/03/31 17:41:58]

I don't quite understand what having a separate visual viewport for a guest
means, either. This seems reasonable to me, but do we expect to be able to
separately scale a guest from its embedder?

+  bool is_guest = BrowserPluginGuest::IsGuest(
+      static_cast<RenderViewHostImpl*>(RenderViewHost::From(host_)));
+  if (frame_connector_ && !is_guest) {
+    RenderWidgetHostView* parent_view =
+        frame_connector_->GetParentRenderWidgetHostView();
+    // The parent_view can be null in unit tests when using a TestWebContents.
+    if (parent_view)
+      return parent_view->GetVisibleViewportSize();
+  }
+  return GetViewBounds().size();
+}
+
 gfx::Vector2dF RenderWidgetHostViewChildFrame::GetLastScrollOffset() const {
   return last_scroll_offset_;
 }
 
 gfx::NativeView RenderWidgetHostViewChildFrame::GetNativeView() const {
   NOTREACHED();
   return NULL;
 }
 
 gfx::NativeViewId RenderWidgetHostViewChildFrame::GetNativeViewId() const {
@@ skipping 435 matching lines @@
   if (surface_factory_ && !surface_id_.is_null())
     surface_factory_->Destroy(surface_id_);
   surface_id_ = cc::SurfaceId();
 }
 
 cc::SurfaceId RenderWidgetHostViewChildFrame::SurfaceIdForTesting() const {
   return surface_id_;
 };
 
 }  // namespace content