Hide fullscreen rotation jank

content/browser/renderer_host/render_widget_host_view_android.h

Index: content/browser/renderer_host/render_widget_host_view_android.h
diff --git a/content/browser/renderer_host/render_widget_host_view_android.h b/content/browser/renderer_host/render_widget_host_view_android.h
index 6846edce443679b5027edc4a970db758f0052c54..db8532aacf7026e18ff8df17b943a75d219101a9 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.h
+++ b/content/browser/renderer_host/render_widget_host_view_android.h
@@ -238,6 +238,11 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
   // Non-virtual methods
   void SetContentViewCore(ContentViewCoreImpl* content_view_core);
   SkColor GetCachedBackgroundColor() const;
+  bool can_show_thumbnail_placeholder() const {

[Khushal, 2017/06/14 19:43:14]

nit: not a trivial accessor. CanShowThumbnailPlaceholder and define in .cc?

[steimel, 2017/06/14 21:46:16]

Done.

+    return !(fullscreen_state_ == FullscreenState::kEnteringFullscreen ||
+             fullscreen_state_ == FullscreenState::kExitingFullscreen ||
+             fullscreen_state_ == FullscreenState::kFullscreenRotation);
+  }
   void SendKeyEvent(const NativeWebKeyboardEvent& event);
   void SendMouseEvent(const ui::MotionEventAndroid&, int action_button);
   void SendMouseWheelEvent(const blink::WebMouseWheelEvent& event);
@@ -263,6 +268,8 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
 
   void WasResized();
 
+  void OnFullscreenStateChanged(bool entered_fullscreen);
+
   bool HasValidFrame() const;
 
   void MoveCaret(const gfx::Point& point);
@@ -349,6 +356,15 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
 
   WebContentsAccessibilityAndroid* GetWebContentsAccessibilityAndroid() const;
 
+  void EvictFrameIfNecessary(bool physical_backing_resized);
+  enum class FullscreenState {

[Khushal, 2017/06/14 19:43:14]

nit: Generally this would be at the beginning of the private declarations.

[steimel, 2017/06/14 21:46:16]

Done.

+    kNotFullscreen,
+    kEnteringFullscreen,
+    kFullscreen,
+    kExitingFullscreen,
+    kFullscreenRotation,
+  };
+
   // The model object.
   RenderWidgetHostImpl* host_;
 
@@ -428,6 +444,11 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
   float prev_top_shown_pix_;
   float prev_bottom_shown_pix_;
 
+  FullscreenState fullscreen_state_ = FullscreenState::kNotFullscreen;
+  bool awaiting_resize_ = false;

[Khushal, 2017/06/14 19:43:14]

nit: fullscreen_transition_awaiting_resize_?

And could you add a comment documenting the use? There are 2 things to note:

1) We are assuming that every transition to/from fullscreen will be followed by
a change in view's physical backing size (which is basically the android Surface
size).

2) And while we could simply take a mismatch in fullscreen states as the trigger
for a transition, and assume the transition to have finished once the fullscreen
states and sizes match, we have cases where we reach this consistent state
before the physical backing size changes. Which is why we defer assuming the
transition to be completed until a resize event is received.

[steimel, 2017/06/14 21:46:16]

Done.

+  bool current_frame_is_fullscreen_ = false;
+  bool web_contents_is_fullscreen_ = false;
+
   cc::mojom::MojoCompositorFrameSinkClient* renderer_compositor_frame_sink_ =
       nullptr;