Renamed ChannelObserver to better describe its purpose

In the ozone drm platform, the ChannelObserver watches for changes
on the IPC channel. However, ozone/drm will soon support execute in
an in-process mode for MUS and the existing multi-process mode.
Rename the class to reflect this.

BUG=558602

Review URL: https://codereview.chromium.org/1603213002

Cr-Commit-Position: refs/heads/master@{#371920}

ui/ozone/platform/drm/BUILD.gn

@@ -87,7 +87,6 @@ source_set("gbm") {
     "gpu/scanout_buffer.h",
     "gpu/screen_manager.cc",
     "gpu/screen_manager.h",
-    "host/channel_observer.h",
     "host/drm_cursor.cc",
     "host/drm_cursor.h",
     "host/drm_cursor_core.cc",
@@ -114,6 +113,7 @@ source_set("gbm") {
     "host/drm_window_host.h",
     "host/drm_window_host_manager.cc",
     "host/drm_window_host_manager.h",
+    "host/gpu_thread_observer.h",
     "ozone_platform_gbm.cc",
     "ozone_platform_gbm.h",
   ]

ui/ozone/platform/drm/gbm.gypi

@@ -121,7 +121,6 @@
         'gpu/proxy_helpers.h',
         'gpu/screen_manager.cc',
         'gpu/screen_manager.h',
-        'host/channel_observer.h',
         'host/drm_cursor.cc',
         'host/drm_cursor.h',
         'host/drm_cursor_core.cc',
@@ -148,6 +147,7 @@
         'host/drm_window_host.h',
         'host/drm_window_host_manager.cc',
         'host/drm_window_host_manager.h',
+        'host/gpu_thread_observer.h',
         'ozone_platform_gbm.cc',
         'ozone_platform_gbm.h',
       ],

ui/ozone/platform/drm/host/drm_display_host.cc

@@ -18,11 +18,11 @@ DrmDisplayHost::DrmDisplayHost(DrmGpuPlatformSupportHost* sender,
     : sender_(sender),
       snapshot_(new DisplaySnapshotProxy(params)),
       is_dummy_(is_dummy) {
-  sender_->AddChannelObserver(this);
+  sender_->AddGpuThreadObserver(this);
 }
 
 DrmDisplayHost::~DrmDisplayHost() {
-  sender_->RemoveChannelObserver(this);
+  sender_->RemoveGpuThreadObserver(this);
   ClearCallbacks();
 }
 
@@ -107,7 +107,7 @@ void DrmDisplayHost::SetGammaRamp(const std::vector<GammaRampRGBEntry>& lut) {
   sender_->Send(new OzoneGpuMsg_SetGammaRamp(snapshot_->display_id(), lut));
 }
 
-void DrmDisplayHost::OnChannelEstablished() {
+void DrmDisplayHost::OnGpuThreadReady() {
   is_dummy_ = false;
 
   // Note: These responses are done here since the OnChannelDestroyed() is
@@ -115,8 +115,7 @@ void DrmDisplayHost::OnChannelEstablished() {
   ClearCallbacks();
 }
 
-void DrmDisplayHost::OnChannelDestroyed() {
-}
+void DrmDisplayHost::OnGpuThreadRetired() {}
 
 void DrmDisplayHost::ClearCallbacks() {
   if (!configure_callback_.is_null())

ui/ozone/platform/drm/host/drm_display_host.h

@@ -9,7 +9,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "ui/display/types/display_constants.h"
 #include "ui/display/types/native_display_delegate.h"
-#include "ui/ozone/platform/drm/host/channel_observer.h"
+#include "ui/ozone/platform/drm/host/gpu_thread_observer.h"
 
 namespace ui {
 
@@ -17,7 +17,7 @@ struct DisplaySnapshot_Params;
 class DisplaySnapshot;
 class DrmGpuPlatformSupportHost;
 
-class DrmDisplayHost : public ChannelObserver {
+class DrmDisplayHost : public GpuThreadObserver {
  public:
   DrmDisplayHost(DrmGpuPlatformSupportHost* sender,
                  const DisplaySnapshot_Params& params,
@@ -40,9 +40,9 @@ class DrmDisplayHost : public ChannelObserver {
   void OnHDCPStateReceived(bool status, HDCPState state);
   void OnHDCPStateUpdated(bool status);
 
-  // ChannelObserver:
-  void OnChannelEstablished() override;
-  void OnChannelDestroyed() override;
+  // GpuThreadObserver:
+  void OnGpuThreadReady() override;
+  void OnGpuThreadRetired() override;
 
  private:
   // Calls all the callbacks with failure.

ui/ozone/platform/drm/host/drm_gpu_platform_support_host.cc

@@ -9,8 +9,8 @@
 #include "base/trace_event/trace_event.h"
 #include "ui/ozone/common/gpu/ozone_gpu_message_params.h"
 #include "ui/ozone/common/gpu/ozone_gpu_messages.h"
-#include "ui/ozone/platform/drm/host/channel_observer.h"
 #include "ui/ozone/platform/drm/host/drm_cursor.h"
+#include "ui/ozone/platform/drm/host/gpu_thread_observer.h"
 
 namespace ui {
 
@@ -37,16 +37,17 @@ void DrmGpuPlatformSupportHost::UnregisterHandler(
     handlers_.erase(it);
 }
 
-void DrmGpuPlatformSupportHost::AddChannelObserver(ChannelObserver* observer) {
-  channel_observers_.AddObserver(observer);
+void DrmGpuPlatformSupportHost::AddGpuThreadObserver(
+    GpuThreadObserver* observer) {
+  gpu_thread_observers_.AddObserver(observer);
 
   if (IsConnected())
-    observer->OnChannelEstablished();
+    observer->OnGpuThreadReady();
 }
 
-void DrmGpuPlatformSupportHost::RemoveChannelObserver(
-    ChannelObserver* observer) {
-  channel_observers_.RemoveObserver(observer);
+void DrmGpuPlatformSupportHost::RemoveGpuThreadObserver(
+    GpuThreadObserver* observer) {
+  gpu_thread_observers_.RemoveObserver(observer);
 }
 
 bool DrmGpuPlatformSupportHost::IsConnected() {
@@ -66,8 +67,8 @@ void DrmGpuPlatformSupportHost::OnChannelEstablished(
   for (size_t i = 0; i < handlers_.size(); ++i)
     handlers_[i]->OnChannelEstablished(host_id, send_runner_, send_callback_);
 
-  FOR_EACH_OBSERVER(ChannelObserver, channel_observers_,
-                    OnChannelEstablished());
+  FOR_EACH_OBSERVER(GpuThreadObserver, gpu_thread_observers_,
+                    OnGpuThreadReady());
 
   // The cursor is special since it will process input events on the IO thread
   // and can by-pass the UI thread. This means that we need to special case it
@@ -86,8 +87,8 @@ void DrmGpuPlatformSupportHost::OnChannelDestroyed(int host_id) {
     host_id_ = -1;
     send_runner_ = nullptr;
     send_callback_.Reset();
-    FOR_EACH_OBSERVER(ChannelObserver, channel_observers_,
-                      OnChannelDestroyed());
+    FOR_EACH_OBSERVER(GpuThreadObserver, gpu_thread_observers_,
+                      OnGpuThreadRetired());
   }
 
   for (size_t i = 0; i < handlers_.size(); ++i)

ui/ozone/platform/drm/host/drm_gpu_platform_support_host.h

@@ -20,8 +20,8 @@ class Point;
 
 namespace ui {
 
-class ChannelObserver;
 class DrmCursor;
+class GpuThreadObserver;
 
 class DrmGpuPlatformSupportHost : public GpuPlatformSupportHost,
                                   public IPC::Sender {
@@ -32,8 +32,8 @@ class DrmGpuPlatformSupportHost : public GpuPlatformSupportHost,
   void RegisterHandler(GpuPlatformSupportHost* handler);
   void UnregisterHandler(GpuPlatformSupportHost* handler);
 
-  void AddChannelObserver(ChannelObserver* observer);
-  void RemoveChannelObserver(ChannelObserver* observer);
+  void AddGpuThreadObserver(GpuThreadObserver* observer);
+  void RemoveGpuThreadObserver(GpuThreadObserver* observer);
 
   bool IsConnected();
 
@@ -58,7 +58,7 @@ class DrmGpuPlatformSupportHost : public GpuPlatformSupportHost,
 
   std::vector<GpuPlatformSupportHost*> handlers_;  // Not owned.
   DrmCursor* cursor_;                              // Not owned.
-  base::ObserverList<ChannelObserver> channel_observers_;
+  base::ObserverList<GpuThreadObserver> gpu_thread_observers_;
 };
 
 }  // namespace ui

ui/ozone/platform/drm/host/drm_window_host.cc

@@ -47,12 +47,12 @@ DrmWindowHost::~DrmWindowHost() {
   window_manager_->RemoveWindow(widget_);
   cursor_->OnWindowRemoved(widget_);
 
-  sender_->RemoveChannelObserver(this);
+  sender_->RemoveGpuThreadObserver(this);
   sender_->Send(new OzoneGpuMsg_DestroyWindow(widget_));
 }
 
 void DrmWindowHost::Initialize() {
-  sender_->AddChannelObserver(this);
+  sender_->AddGpuThreadObserver(this);
   PlatformEventSource::GetInstance()->AddPlatformEventDispatcher(this);
   cursor_->OnWindowAdded(widget_, bounds_, GetCursorConfinedBounds());
   delegate_->OnAcceleratedWidgetAvailable(widget_, 1.f);
@@ -188,13 +188,12 @@ uint32_t DrmWindowHost::DispatchEvent(const PlatformEvent& native_event) {
   return POST_DISPATCH_STOP_PROPAGATION;
 }
 
-void DrmWindowHost::OnChannelEstablished() {
+void DrmWindowHost::OnGpuThreadReady() {
   sender_->Send(new OzoneGpuMsg_CreateWindow(widget_));
   SendBoundsChange();
 }
 
-void DrmWindowHost::OnChannelDestroyed() {
-}
+void DrmWindowHost::OnGpuThreadRetired() {}
 
 void DrmWindowHost::SendBoundsChange() {
   // Update the cursor before the window so that the cursor stays within the

ui/ozone/platform/drm/host/drm_window_host.h

@@ -13,7 +13,7 @@
 #include "ui/events/platform/platform_event_dispatcher.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/native_widget_types.h"
-#include "ui/ozone/platform/drm/host/channel_observer.h"
+#include "ui/ozone/platform/drm/host/gpu_thread_observer.h"
 #include "ui/platform_window/platform_window.h"
 
 namespace ui {
@@ -38,7 +38,7 @@ class EventFactoryEvdev;
 // associated with the window (the surface is created on the GPU process).
 class DrmWindowHost : public PlatformWindow,
                       public PlatformEventDispatcher,
-                      public ChannelObserver {
+                      public GpuThreadObserver {
  public:
   DrmWindowHost(PlatformWindowDelegate* delegate,
                 const gfx::Rect& bounds,
@@ -79,8 +79,8 @@ class DrmWindowHost : public PlatformWindow,
   uint32_t DispatchEvent(const PlatformEvent& event) override;
 
   // ChannelObserver:
-  void OnChannelEstablished() override;
-  void OnChannelDestroyed() override;
+  void OnGpuThreadReady() override;
+  void OnGpuThreadRetired() override;
 
  private:
   void SendBoundsChange();

ui/ozone/platform/drm/host/drm_window_host_manager.h

@@ -17,7 +17,6 @@ class Point;
 
 namespace ui {
 
-class DrmGpuPlatformSupportHost;
 class DrmWindowHost;
 
 // Responsible for keeping the mapping between the allocated widgets and

ui/ozone/platform/drm/host/channel_observer.h → ui/ozone/platform/drm/host/gpu_thread_observer.h

@@ -2,20 +2,23 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef UI_OZONE_PLATFORM_DRM_HOST_CHANNEL_OBSERVER_H_
-#define UI_OZONE_PLATFORM_DRM_HOST_CHANNEL_OBSERVER_H_
+#ifndef UI_OZONE_PLATFORM_DRM_HOST_GPU_THREAD_OBSERVER_H_
+#define UI_OZONE_PLATFORM_DRM_HOST_GPU_THREAD_OBSERVER_H_
 
 namespace ui {
 
 // Observes the channel state.
-class ChannelObserver {
+class GpuThreadObserver {
  public:
-  virtual ~ChannelObserver() {}
+  virtual ~GpuThreadObserver() {}
 
-  virtual void OnChannelEstablished() = 0;
-  virtual void OnChannelDestroyed() = 0;
+  // Called when a GPU thread implementation has become available.
+  virtual void OnGpuThreadReady() = 0;
+  // Called when the GPU thread implementation has ceased to be
+  // available.
+  virtual void OnGpuThreadRetired() = 0;
 };
 
 }  // namespace ui
 
-#endif  // UI_OZONE_PLATFORM_DRM_HOST_CHANNEL_OBSERVER_H_
+#endif  // UI_OZONE_PLATFORM_DRM_HOST_GPU_THREAD_OBSERVER_H_