mac: Take previous RWHVMac contents at navigation

When navigating, make the old RHWVMac dump its ui::Compositor in
TakeFallbackContentFrom, and have the new RWHVMac pick it up.

Ensure that the ui::AcceleratedWidgetMac preserve its contents through
this transition.

This is not enough to completely eliminate all flashes, because the
NSViews in play aren't being atomically swapped.

Bug: 829523
Change-Id: Ica6eab8dcea7a7987e8b7f83dbfd24acb2c6f7c4
Reviewed-on: https://chromium-review.googlesource.com/1023653
Commit-Queue: ccameron <ccameron@chromium.org>
Reviewed-by: Saman Sami <samans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552954}

content/browser/renderer_host/browser_compositor_view_mac.h

@@ -70,6 +70,7 @@ class CONTENT_EXPORT BrowserCompositorMac : public DelegatedFrameHostClient {
                              const base::TimeDelta& interval);
   void SetNeedsBeginFrames(bool needs_begin_frames);
   void SetWantsAnimateOnlyBeginFrames();
+  void TakeFallbackContentFrom(BrowserCompositorMac* other);
 
   // Update the renderer's SurfaceId to reflect the current dimensions of the
   // NSView. This will allocate a new SurfaceId if needed. This will return

content/browser/renderer_host/browser_compositor_view_mac.mm

@@ -423,6 +423,21 @@ void BrowserCompositorMac::SetWantsAnimateOnlyBeginFrames() {
   delegated_frame_host_->SetWantsAnimateOnlyBeginFrames();
 }
 
+void BrowserCompositorMac::TakeFallbackContentFrom(
+    BrowserCompositorMac* other) {
+  // We will have a flash if we can't recycle the compositor from |other|.
+  if (other->state_ != HasDetachedCompositor || state_ != HasNoCompositor) {
+    return;
+  }
+
+  delegated_frame_host_->TakeFallbackContentFrom(
+      other->delegated_frame_host_.get());
+  other->recyclable_compositor_->accelerated_widget_mac()
+      ->ResetNSViewPreservingContents();
+  other->TransitionToState(HasNoCompositor);
+  TransitionToState(HasAttachedCompositor);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // DelegatedFrameHost, public:
 

content/browser/renderer_host/render_widget_host_ns_view_client.h

@@ -6,7 +6,31 @@
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_NS_VIEW_CLIENT_H_
 
 #include "base/macros.h"
+#include "base/strings/string16.h"
+#include "content/common/edit_command.h"
 #include "content/common/mac/attributed_string_coder.h"
+#include "ui/base/ime/ime_text_span.h"
+#include "ui/base/ime/text_input_type.h"
+
+namespace blink {
+class WebGestureEvent;
+class WebMouseEvent;
+class WebMouseWheelEvent;
+}  // namespace blink
+
+namespace display {
+class Display;
+}  // namespace display
+
+namespace gfx {
+class PointF;
+class Range;
+class Rect;
+}  // namespace gfx
+
+namespace ui {
+class LatencyInfo;
+}  // namespace ui
 
 namespace content {
 

content/browser/renderer_host/render_widget_host_view_mac.mm

@@ -711,8 +711,16 @@ void RenderWidgetHostViewMac::SetWantsAnimateOnlyBeginFrames() {
 
 void RenderWidgetHostViewMac::TakeFallbackContentFrom(
     RenderWidgetHostView* view) {
-  SetBackgroundColor(view->background_color());
-  // TODO(crbug.com/829523): Implement this.
+  DCHECK(!static_cast<RenderWidgetHostViewBase*>(view)
+              ->IsRenderWidgetHostViewChildFrame());
+  DCHECK(!static_cast<RenderWidgetHostViewBase*>(view)
+              ->IsRenderWidgetHostViewGuest());
+  RenderWidgetHostViewMac* view_mac =
+      static_cast<RenderWidgetHostViewMac*>(view);
+  ScopedCAActionDisabler disabler;
+  SetBackgroundColor(view_mac->background_color());
+  browser_compositor_->TakeFallbackContentFrom(
+      view_mac->browser_compositor_.get());
 }
 
 bool RenderWidgetHostViewMac::GetLineBreakIndex(

ui/accelerated_widget_mac/accelerated_widget_mac.h

@@ -58,6 +58,7 @@ class ACCELERATED_WIDGET_MAC_EXPORT AcceleratedWidgetMac
 
   void SetNSView(AcceleratedWidgetMacNSView* view);
   void ResetNSView();
+  void ResetNSViewPreservingContents();
 
   // Return true if the last frame swapped has a size in DIP of |dip_size|.
   bool HasFrameOfSize(const gfx::Size& dip_size) const;

ui/accelerated_widget_mac/accelerated_widget_mac.mm

@@ -94,6 +94,15 @@ void AcceleratedWidgetMac::ResetNSView() {
   view_ = NULL;
 }
 
+void AcceleratedWidgetMac::ResetNSViewPreservingContents() {
+  if (!view_)
+    return;
+
+  ScopedCAActionDisabler disabler;
+  [flipped_layer_ removeFromSuperlayer];
+  view_ = NULL;
+}
+
 bool AcceleratedWidgetMac::HasFrameOfSize(
     const gfx::Size& dip_size) const {
   return last_swap_size_dip_ == dip_size;