Revert of Separate RenderView from RenderWidget, part 1: inheritance. (patchset #2 id:20001 of https://codereview.chromium.org/1674543004/ )

Reason for revert:
Many tests are crashing on Linux-dbg https://codereview.chromium.org/1674543004

Original issue's description:
> Separate RenderView from RenderWidget, part 1: inheritance.
>
> Make RenderViewImpl able to privately inherit from RenderWidget. We can't switch over yet because WebTestProxy has weird templating stuff that can't support it.
>
> BUG=583347
> TEST=all green
> CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel,mac_blink_rel,win_blink_rel;tryserver.chromium.linux:linux_site_isolation
>
> Committed: https://crrev.com/42e463ac3a6f667821a8bed78ba0eafde79a7bfc
> Cr-Commit-Position: refs/heads/master@{#378276}

TBR=dcheng@chromium.org,avi@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=583347

Review URL: https://codereview.chromium.org/1750863002

Cr-Commit-Position: refs/heads/master@{#378366}

3 files changed, 22 insertions, 19 deletions

diff --git a/content/public/renderer/render_view.h b/content/public/renderer/render_view.h
index 2a7f85a..f913f64 100644
--- a/content/public/renderer/render_view.h
+++ b/content/public/renderer/render_view.h
@@ -39,7 +39,6 @@ class Size;
 namespace content {
 
 class RenderFrame;
-class RenderWidget;
 class RenderViewVisitor;
 struct SSLStatus;
 struct WebPreferences;
@@ -68,9 +67,6 @@ class CONTENT_EXPORT RenderView : public IPC::Sender {
   static void ApplyWebPreferences(const WebPreferences& preferences,
                                   blink::WebView* web_view);
 
-  // Returns the RenderWidget for this RenderView.
-  virtual RenderWidget* GetWidget() const = 0;
-
   // Returns the main RenderFrame.
   virtual RenderFrame* GetMainRenderFrame() = 0;
 
diff --git a/content/public/renderer/render_view_observer.cc b/content/public/renderer/render_view_observer.cc
index 5e876cc..8289da9 100644
--- a/content/public/renderer/render_view_observer.cc
+++ b/content/public/renderer/render_view_observer.cc
@@ -6,22 +6,27 @@
 
 #include "content/renderer/render_view_impl.h"
 
+using blink::WebFrame;
+
 namespace content {
 
 RenderViewObserver::RenderViewObserver(RenderView* render_view)
-    : render_view_(static_cast<RenderViewImpl*>(render_view)),
+    : render_view_(render_view),
       routing_id_(MSG_ROUTING_NONE) {
-  // |render_view_| can be null on unit testing or if Observe() is used.
-  if (render_view_) {
-    routing_id_ = render_view_->GetRoutingID();
+  // |render_view| can be NULL on unit testing or if Observe() is used.
+  if (render_view) {
+    RenderViewImpl* impl = static_cast<RenderViewImpl*>(render_view);
+    routing_id_ = impl->routing_id();
     // TODO(jam): bring this back DCHECK_NE(routing_id_, MSG_ROUTING_NONE);
-    render_view_->AddObserver(this);
+    impl->AddObserver(this);
   }
 }
 
 RenderViewObserver::~RenderViewObserver() {
-  if (render_view_)
-    render_view_->RemoveObserver(this);
+  if (render_view_) {
+    RenderViewImpl* impl = static_cast<RenderViewImpl*>(render_view_);
+    impl->RemoveObserver(this);
+  }
 }
 
 void RenderViewObserver::OnDestruct() {
@@ -45,19 +50,21 @@ RenderView* RenderViewObserver::render_view() const {
 }
 
 void RenderViewObserver::RenderViewGone() {
-  render_view_ = nullptr;
+  render_view_ = NULL;
 }
 
 void RenderViewObserver::Observe(RenderView* render_view) {
-  if (render_view_) {
-    render_view_->RemoveObserver(this);
+  RenderViewImpl* impl = static_cast<RenderViewImpl*>(render_view_);
+  if (impl) {
+    impl->RemoveObserver(this);
     routing_id_ = 0;
   }
 
-  render_view_ = static_cast<RenderViewImpl*>(render_view);
-  if (render_view_) {
-    routing_id_ = render_view_->GetRoutingID();
-    render_view_->AddObserver(this);
+  render_view_ = render_view;
+  impl = static_cast<RenderViewImpl*>(render_view_);
+  if (impl) {
+    routing_id_ = impl->routing_id();
+    impl->AddObserver(this);
   }
 }
 
diff --git a/content/public/renderer/render_view_observer.h b/content/public/renderer/render_view_observer.h
index a245e63..5eeb45b 100644
--- a/content/public/renderer/render_view_observer.h
+++ b/content/public/renderer/render_view_observer.h
@@ -103,7 +103,7 @@ class CONTENT_EXPORT RenderViewObserver : public IPC::Listener,
   // can null out its pointer.
   void RenderViewGone();
 
-  RenderViewImpl* render_view_;
+  RenderView* render_view_;
   // The routing ID of the associated RenderView.
   int routing_id_;