Make 1.5x DPI text render crisply.

content/browser/web_contents/web_contents_view_aura.cc

Index: content/browser/web_contents/web_contents_view_aura.cc
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index f0cce6521220a903c2b50270e36df23258510291..eaefc275b47d4924d9565e4d6b1b93c19c9f017e 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -547,6 +547,12 @@ class WebContentsViewAura::WindowObserver
     if (window != view_->window_)
       return;
 
+    // Use the new parent's root window for calculating HiDPI subpixel offset.
+    RenderWidgetHostViewAura* rwhv = ToRenderWidgetHostViewAura(
+        view_->web_contents_->GetRenderWidgetHostView());
+    if (rwhv)
+      rwhv->SnapToPhysicalPixelBoundary();
+
     aura::Window* host_window =
         window->GetProperty(aura::client::kHostWindowKey);
     if (!host_window)
@@ -561,10 +567,8 @@ class WebContentsViewAura::WindowObserver
       for (size_t i = 0; i < children.size(); ++i)
         children[i]->RemoveObserver(this);
 
-      RenderWidgetHostViewAura* view = ToRenderWidgetHostViewAura(
-          view_->web_contents_->GetRenderWidgetHostView());
-      if (view)
-        view->UpdateConstrainedWindowRects(std::vector<gfx::Rect>());
+      if (rwhv)
+        rwhv->UpdateConstrainedWindowRects(std::vector<gfx::Rect>());
     }
 
     // When we get parented to the root window, the code below will watch the