Make 1.5x DPI text render crisply.

content/browser/web_contents/web_contents_view_aura.cc

 // Copyright (c) 2012 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/web_contents/web_contents_view_aura.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/metrics/histogram.h"
@@ skipping 529 matching lines @@
       UpdateConstrainedWindows(NULL);
     }
   }
 #endif
 
   virtual void OnWindowParentChanged(aura::Window* window,
                                      aura::Window* parent) OVERRIDE {
     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)
       host_window = parent;
 
     if (host_window_)
       host_window_->RemoveObserver(this);
 
 #if defined(OS_WIN)
     if (host_window_) {
       const aura::Window::Windows& children = host_window_->children();
       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
     // host window, aka root window. Since we already watch the root window on
     // Windows, unregister first so that the debug check doesn't fire.
     if (host_window && host_window == window->GetRootWindow())
       host_window->RemoveObserver(this);
 
     // We need to undo the above if we were parented to the root window and then
     // got parented to another window. At that point, the code before the ifdef
@@ skipping 1022 matching lines @@
   if (visible) {
     if (!web_contents_->should_normally_be_visible())
       web_contents_->WasShown();
   } else {
     if (web_contents_->should_normally_be_visible())
       web_contents_->WasHidden();
   }
 }
 
 }  // namespace content