[Ozone-DRI] Add display observer

Introduce a display change observer and make the window delegates update
their cached HardwareDisplayController pointer as a result of changes in
ScreenManager.

BUG=446184
NOTRY=true

Review URL: https://codereview.chromium.org/844343002

Cr-Commit-Position: refs/heads/master@{#311112}

Review URL: https://codereview.chromium.org/855153002

Cr-Commit-Position: refs/branch-heads/2272@{#40}
Cr-Branched-From: 827a380-refs/heads/master@{#310958}

ui/ozone/platform/dri/BUILD.gn

@@ -14,6 +14,7 @@ source_set("dri_common") {
     "channel_observer.h",
     "crtc_controller.cc",
     "crtc_controller.h",
+    "display_change_observer.h",
     "display_manager.cc",
     "display_manager.h",
     "display_mode_dri.cc",

ui/ozone/platform/dri/display_change_observer.h

@@ -0,0 +1,26 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_OZONE_PLATFORM_DRI_DISPLAY_CHANGE_OBSERVER_H_
+#define UI_OZONE_PLATFORM_DRI_DISPLAY_CHANGE_OBSERVER_H_
+
+namespace ui {
+
+class HardwareDisplayController;
+
+class DisplayChangeObserver {
+ public:
+  virtual ~DisplayChangeObserver() {}
+
+  // Called when |controller| was changed/added.
+  virtual void OnDisplayChanged(HardwareDisplayController* controller) = 0;
+
+  // Called just before |controller| is removed. Observers that cached
+  // |controller| must invalidate it at this point.
+  virtual void OnDisplayRemoved(HardwareDisplayController* controller) = 0;
+};
+
+}  // namespace ui
+
+#endif  // UI_OZONE_PLATFORM_DRI_DISPLAY_CHANGE_OBSERVER_H_

ui/ozone/platform/dri/dri.gypi

@@ -38,6 +38,7 @@
         'channel_observer.h',
         'crtc_controller.cc',
         'crtc_controller.h',
+        'display_change_observer.h',
         'display_manager.cc',
         'display_manager.h',
         'display_mode_dri.cc',

ui/ozone/platform/dri/dri_window_delegate_impl.cc

@@ -61,6 +61,8 @@ DriWindowDelegateImpl::~DriWindowDelegateImpl() {
 void DriWindowDelegateImpl::Initialize() {
   TRACE_EVENT1("dri", "DriWindowDelegateImpl::Initialize", "widget", widget_);
 
+  screen_manager_->AddObserver(this);
+
   uint64_t cursor_width = 64;
   uint64_t cursor_height = 64;
   drm_->GetCapability(DRM_CAP_CURSOR_WIDTH, &cursor_width);
@@ -78,19 +80,21 @@ void DriWindowDelegateImpl::Initialize() {
 
 void DriWindowDelegateImpl::Shutdown() {
   TRACE_EVENT1("dri", "DriWindowDelegateImpl::Shutdown", "widget", widget_);
+  screen_manager_->RemoveObserver(this);
 }
 
 gfx::AcceleratedWidget DriWindowDelegateImpl::GetAcceleratedWidget() {
   return widget_;
 }
 
 HardwareDisplayController* DriWindowDelegateImpl::GetController() {
-  return controller_.get();
+  return controller_;
 }
 
 void DriWindowDelegateImpl::OnBoundsChanged(const gfx::Rect& bounds) {
   TRACE_EVENT2("dri", "DriWindowDelegateImpl::OnBoundsChanged", "widget",
                widget_, "bounds", bounds.ToString());
+  bounds_ = bounds;
   controller_ = screen_manager_->GetDisplayController(bounds);
 }
 
@@ -128,6 +132,30 @@ void DriWindowDelegateImpl::MoveCursor(const gfx::Point& location) {
     controller_->MoveCursor(location);
 }
 
+void DriWindowDelegateImpl::OnDisplayChanged(
+    HardwareDisplayController* controller) {
+  DCHECK(controller);
+
+  gfx::Rect controller_bounds =
+      gfx::Rect(controller->origin(), controller->GetModeSize());
+  if (controller_) {
+    if (controller_ != controller)
+      return;
+
+    if (controller->IsDisabled() || bounds_ != controller_bounds)
+      controller_ = nullptr;
+  } else {
+    if (bounds_ == controller_bounds && !controller->IsDisabled())
+      controller_ = controller;
+  }
+}
+
+void DriWindowDelegateImpl::OnDisplayRemoved(
+    HardwareDisplayController* controller) {
+  if (controller_ == controller)
+    controller_ = nullptr;
+}
+
 void DriWindowDelegateImpl::ResetCursor(bool bitmap_only) {
   if (cursor_bitmaps_.size()) {
     // Draw new cursor into backbuffer.

ui/ozone/platform/dri/dri_window_delegate_impl.h

@@ -5,16 +5,13 @@
 #ifndef UI_OZONE_PLATFORM_DRI_DRI_WINDOW_DELEGATE_IMPL_H_
 #define UI_OZONE_PLATFORM_DRI_DRI_WINDOW_DELEGATE_IMPL_H_
 
-#include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 #include "ui/gfx/geometry/point.h"
+#include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/native_widget_types.h"
+#include "ui/ozone/platform/dri/display_change_observer.h"
 #include "ui/ozone/platform/dri/dri_window_delegate.h"
 
-namespace gfx {
-class Rect;
-}  // namespace gfx
-
 namespace ui {
 
 class DriBuffer;
@@ -23,7 +20,8 @@ class DriWrapper;
 class HardwareDisplayController;
 class ScreenManager;
 
-class DriWindowDelegateImpl : public DriWindowDelegate {
+class DriWindowDelegateImpl : public DriWindowDelegate,
+                              public DisplayChangeObserver {
  public:
   DriWindowDelegateImpl(gfx::AcceleratedWidget widget,
                         DriWrapper* drm,
@@ -44,6 +42,10 @@ class DriWindowDelegateImpl : public DriWindowDelegate {
                                   const gfx::Point& location) override;
   void MoveCursor(const gfx::Point& location) override;
 
+  // DisplayChangeObserver:
+  void OnDisplayChanged(HardwareDisplayController* controller) override;
+  void OnDisplayRemoved(HardwareDisplayController* controller) override;
+
  private:
   // Draw the last set cursor & update the cursor plane.
   void ResetCursor(bool bitmap_only);
@@ -57,7 +59,12 @@ class DriWindowDelegateImpl : public DriWindowDelegate {
   DriWindowDelegateManager* window_manager_;  // Not owned.
   ScreenManager* screen_manager_;             // Not owned.
 
-  base::WeakPtr<HardwareDisplayController> controller_;
+  // The current bounds of the window.
+  gfx::Rect bounds_;
+
+  // The controller associated with the current window. This may be nullptr if
+  // the window isn't over an active display.
+  HardwareDisplayController* controller_;
 
   base::RepeatingTimer<DriWindowDelegateImpl> cursor_timer_;
 

ui/ozone/platform/dri/screen_manager.cc

@@ -89,8 +89,11 @@ void ScreenManager::RemoveDisplayController(uint32_t crtc) {
   if (it != controllers_.end()) {
     bool is_mirrored = (*it)->IsMirrored();
     (*it)->RemoveCrtc(crtc);
-    if (!is_mirrored)
+    if (!is_mirrored) {
+      FOR_EACH_OBSERVER(DisplayChangeObserver, observers_,
+                        OnDisplayRemoved(*it));
       controllers_.erase(it);
+    }
   }
 }
 
@@ -105,7 +108,6 @@ bool ScreenManager::ConfigureDisplayController(uint32_t crtc,
                                    << ") doesn't exist.";
 
   HardwareDisplayController* controller = *it;
-  controller = *it;
   // If nothing changed just enable the controller. Note, we perform an exact
   // comparison on the mode since the refresh rate may have changed.
   if (SameMode(mode, controller->get_mode()) &&
@@ -119,6 +121,8 @@ bool ScreenManager::ConfigureDisplayController(uint32_t crtc,
         return HandleMirrorMode(it, mirror, crtc, connector);
     }
 
+    FOR_EACH_OBSERVER(DisplayChangeObserver, observers_,
+                      OnDisplayChanged(controller));
     // Just re-enable the controller to re-use the current state.
     return controller->Enable();
   }
@@ -159,7 +163,7 @@ bool ScreenManager::DisableDisplayController(uint32_t crtc) {
   return false;
 }
 
-base::WeakPtr<HardwareDisplayController> ScreenManager::GetDisplayController(
+HardwareDisplayController* ScreenManager::GetDisplayController(
     const gfx::Rect& bounds) {
   // TODO(dnicoara): Remove hack once TestScreen uses a simple Ozone display
   // configuration reader and ScreenManager is called from there to create the
@@ -170,9 +174,17 @@ base::WeakPtr<HardwareDisplayController> ScreenManager::GetDisplayController(
   HardwareDisplayControllers::iterator it =
       FindActiveDisplayControllerByLocation(bounds);
   if (it != controllers_.end())
-    return (*it)->AsWeakPtr();
+    return *it;
+
+  return nullptr;
+}
+
+void ScreenManager::AddObserver(DisplayChangeObserver* observer) {
+  observers_.AddObserver(observer);
+}
 
-  return base::WeakPtr<HardwareDisplayController>();
+void ScreenManager::RemoveObserver(DisplayChangeObserver* observer) {
+  observers_.RemoveObserver(observer);
 }
 
 ScreenManager::HardwareDisplayControllers::iterator
@@ -244,6 +256,8 @@ bool ScreenManager::ModesetDisplayController(
     return false;
   }
 
+  FOR_EACH_OBSERVER(DisplayChangeObserver, observers_,
+                    OnDisplayChanged(controller));
   return true;
 }
 
@@ -254,6 +268,10 @@ bool ScreenManager::HandleMirrorMode(
     uint32_t connector) {
   (*mirror)->AddCrtc((*original)->RemoveCrtc(crtc));
   if ((*mirror)->Enable()) {
+    FOR_EACH_OBSERVER(DisplayChangeObserver, observers_,
+                      OnDisplayRemoved(*original));
+    FOR_EACH_OBSERVER(DisplayChangeObserver, observers_,
+                      OnDisplayChanged(*mirror));
     controllers_.erase(original);
     return true;
   }

ui/ozone/platform/dri/screen_manager.h

@@ -7,7 +7,8 @@
 
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
-#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#include "ui/ozone/platform/dri/display_change_observer.h"
 #include "ui/ozone/platform/dri/hardware_display_controller.h"
 
 typedef struct _drmModeModeInfo drmModeModeInfo;
@@ -49,13 +50,12 @@ class ScreenManager {
   bool DisableDisplayController(uint32_t crtc);
 
   // Returns a reference to the display controller configured to display within
-  // |bounds|.
-  // This returns a weak reference since the display controller may be destroyed
-  // at any point in time, but the changes are propagated to the compositor much
-  // later (Compositor owns SurfaceOzone*, which is responsible for updating the
-  // display surface).
-  base::WeakPtr<HardwareDisplayController> GetDisplayController(
-      const gfx::Rect& bounds);
+  // |bounds|. If the caller caches the controller it must also register as an
+  // observer to be notified when the controller goes out of scope.
+  HardwareDisplayController* GetDisplayController(const gfx::Rect& bounds);
+
+  void AddObserver(DisplayChangeObserver* observer);
+  void RemoveObserver(DisplayChangeObserver* observer);
 
   // On non CrOS builds there is no display configurator to look-up available
   // displays and initialize the HDCs. In such cases this is called internally
@@ -92,6 +92,8 @@ class ScreenManager {
   // List of display controllers (active and disabled).
   HardwareDisplayControllers controllers_;
 
+  ObserverList<DisplayChangeObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(ScreenManager);
 };