Revert of Snap RWHVA and resize the legacy window on Windows whenever the ancestor window's bounds change. (patchset #12 id:220001 of https://codereview.chromium.org/1062273002/)

Reason for revert:
Speculative, possibly caused lots of browsert_tests redness on a bot that runs browser_tests with an official build (and a different compiler, but all the redness we fixed on official builds so far were caused by the builds being official, not because of the compiler): http://build.chromium.org/p/chromium.fyi/builders/CrWinClang%20tester/builds/285 (see http://crbug.com/467929)

Original issue's description:
> Snap RWHVA and resize the legacy window on Windows whenever the ancestor window's bounds change.
>
> The bookmark bar is hidden through the fast resize code path where in the Renderer is informed about
> the actual size minus the bookmar bar before the bookmark bar is hidden. To ensure that the RWHVA is snapped
> to pixel boundaries and the legacy window is resized we observe bounds changed events on the parent of the WCVA
> window which is the NativeViewHost clipping window. Reason for doing this is the layer for the window hosted by WCVA
> verifies if the stored bounds is the same as the one coming in and ignores the change if yes.
>
> For more context and a general discussion of the reason why this bug happens please visit this link
> https://codereview.chromium.org/1009533005/
>
> BUG=469857, 468669
>
> Committed: https://crrev.com/e6a9b7fff4802ac6796250987be4d52204716392
> Cr-Commit-Position: refs/heads/master@{#324743}

TBR=sky@chromium.org,scottmg@chromium.org,cpu@chromium.org,ananta@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=469857, 468669

Review URL: https://codereview.chromium.org/1063083003

Cr-Commit-Position: refs/heads/master@{#324804}

3 files changed, 15 insertions, 83 deletions

diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index fd85fcc..1463557 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -4,8 +4,6 @@
 
 #include "content/browser/renderer_host/render_widget_host_view_aura.h"
 
-#include <set>
-
 #include "base/auto_reset.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ -354,64 +352,12 @@ class RenderWidgetHostViewAura::WindowObserver : public aura::WindowObserver {
       view_->RemovingFromRootWindow();
   }
 
-  void OnWindowHierarchyChanged(const HierarchyChangeParams& params) override {
-    view_->ParentHierarchyChanged();
-  }
-
  private:
   RenderWidgetHostViewAura* view_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowObserver);
 };
 
-// This class provides functionality to observe the ancestors of the RWHVA for
-// bounds changes. This is done to snap the RWHVA window to a pixel boundary,
-// which could change when the bounds relative to the root changes.
-// An example where this happens is below:-
-// The fast resize code path for bookmarks where in the parent of RWHVA which
-// is WCV has its bounds changed before the bookmark is hidden. This results in
-// the traditional bounds change notification for the WCV reporting the old
-// bounds as the bookmark is still around. Observing all the ancestors of the
-// RWHVA window enables us to know when the bounds of the window relative to
-// root changes and allows us to snap accordingly.
-class RenderWidgetHostViewAura::WindowAncestorObserver
-    : public aura::WindowObserver {
- public:
-  explicit WindowAncestorObserver(RenderWidgetHostViewAura* view)
-      : view_(view) {
-    aura::Window* parent = view_->window_->parent();
-    while (parent) {
-      parent->AddObserver(this);
-      ancestors_.insert(parent);
-      parent = parent->parent();
-    }
-  }
-
-  ~WindowAncestorObserver() override {
-    RemoveAncestorObservers();
-  }
-
-  void OnWindowBoundsChanged(aura::Window* window,
-                             const gfx::Rect& old_bounds,
-                             const gfx::Rect& new_bounds) override {
-    DCHECK(ancestors_.find(window) != ancestors_.end());
-    if (new_bounds.origin() != old_bounds.origin())
-      view_->HandleParentBoundsChanged();
-  }
-
- private:
-  void RemoveAncestorObservers() {
-    for (auto ancestor : ancestors_)
-      ancestor->RemoveObserver(this);
-    ancestors_.clear();
-  }
-
-  RenderWidgetHostViewAura* view_;
-  std::set<aura::Window*> ancestors_;
-
-  DISALLOW_COPY_AND_ASSIGN(WindowAncestorObserver);
-};
-
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewAura, public:
 
@@ -449,7 +395,6 @@ RenderWidgetHostViewAura::RenderWidgetHostViewAura(RenderWidgetHost* host,
     host_->SetView(this);
 
   window_observer_.reset(new WindowObserver(this));
-
   aura::client::SetTooltipText(window_, &tooltip_);
   aura::client::SetActivationDelegate(window_, this);
   aura::client::SetFocusChangeObserver(window_, this);
@@ -789,22 +734,6 @@ bool RenderWidgetHostViewAura::CanRendererHandleEvent(
   return true;
 }
 
-void RenderWidgetHostViewAura::HandleParentBoundsChanged() {
-  SnapToPhysicalPixelBoundary();
-#if defined(OS_WIN)
-  if (legacy_render_widget_host_HWND_) {
-    legacy_render_widget_host_HWND_->SetBounds(
-        window_->GetBoundsInRootWindow());
-  }
-#endif
-}
-
-void RenderWidgetHostViewAura::ParentHierarchyChanged() {
-  ancestor_window_observer_.reset(new WindowAncestorObserver(this));
-  // Snap when we receive a hierarchy changed. http://crbug.com/388908.
-  HandleParentBoundsChanged();
-}
-
 void RenderWidgetHostViewAura::MovePluginWindows(
     const std::vector<WebPluginGeometry>& plugin_window_moves) {
 #if defined(OS_WIN)
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index d9e1201..89bead7 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -401,9 +401,6 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   class WindowObserver;
   friend class WindowObserver;
 
-  class WindowAncestorObserver;
-  friend class WindowAncestorObserver;
-
   void UpdateCursorIfOverSelf();
 
   // Tracks whether SnapToPhysicalPixelBoundary() has been called.
@@ -503,12 +500,6 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
                               bool mouse_locked,
                               bool selection_popup);
 
-  // Called when the parent window bounds change.
-  void HandleParentBoundsChanged();
-
-  // Called when the parent window hierarchy for our window changes.
-  void ParentHierarchyChanged();
-
   // The model object.
   RenderWidgetHostImpl* host_;
 
@@ -518,9 +509,6 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
 
   scoped_ptr<WindowObserver> window_observer_;
 
-  // Tracks the ancestors of the RWHVA window for window location changes.
-  scoped_ptr<WindowAncestorObserver> ancestor_window_observer_;
-
   // Are we in the process of closing?  Tracked so fullscreen views can avoid
   // sending a second shutdown request to the host when they lose the focus
   // after requesting shutdown for another reason (e.g. Escape key).
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index f0d20fa..ce104f2 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -429,6 +429,21 @@ class WebContentsViewAura::WindowObserver
 #endif
   }
 
+  // Overridden from aura::WindowObserver:
+  void OnWindowHierarchyChanged(
+      const aura::WindowObserver::HierarchyChangeParams& params) override {
+    if (params.receiver != view_->window_.get() ||
+        !params.target->Contains(view_->window_.get())) {
+      return;
+    }
+
+    // Use the new parent's root window for calculating HiDPI subpixel offset.
+    RenderWidgetHostViewAura* rwhv = ToRenderWidgetHostViewAura(
+        view_->web_contents_->GetRenderWidgetHostView());
+    if (rwhv)
+      rwhv->SnapToPhysicalPixelBoundary();
+  }
+
 #if defined(OS_WIN)
   // Constrained windows are added as children of the parent's parent's view
   // which may overlap with windowed NPAPI plugins. In that case, tell the RWHV