Revert of Revert of Snap RWHVA and resize the legacy window on Windows whenever the ancestor window's bounds change. (patchset #1 id:1 of https://codereview.chromium.org/1063083003/)

Reason for revert:
Reverting this didn't help, relanding.

Original issue's description:
> 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
>
> Committed: https://crrev.com/67bcbf34229acff21e300e630ee871b0a64871b4
> Cr-Commit-Position: refs/heads/master@{#324804}

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/1050203004

Cr-Commit-Position: refs/heads/master@{#324808}

3 files changed, 83 insertions, 15 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 1463557..fd85fcc 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -4,6 +4,8 @@
 
 #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"
@@ -352,12 +354,64 @@ 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:
 
@@ -395,6 +449,7 @@ 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);
@@ -734,6 +789,22 @@ 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 89bead7..d9e1201 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -401,6 +401,9 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   class WindowObserver;
   friend class WindowObserver;
 
+  class WindowAncestorObserver;
+  friend class WindowAncestorObserver;
+
   void UpdateCursorIfOverSelf();
 
   // Tracks whether SnapToPhysicalPixelBoundary() has been called.
@@ -500,6 +503,12 @@ 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_;
 
@@ -509,6 +518,9 @@ 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 ce104f2..f0d20fa 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -429,21 +429,6 @@ 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