Reland of: [Ozone-GBM] Handle GPU crashes

ui/ozone/platform/dri/gpu_platform_support_host_gbm.cc

Index: ui/ozone/platform/dri/gpu_platform_support_host_gbm.cc
diff --git a/ui/ozone/platform/dri/gpu_platform_support_host_gbm.cc b/ui/ozone/platform/dri/gpu_platform_support_host_gbm.cc
index 160b5153dbd4df2eaddf55892c9c6fab5196251b..fb6acc898afb11eb40dab86480e5013f4ec62fbd 100644
--- a/ui/ozone/platform/dri/gpu_platform_support_host_gbm.cc
+++ b/ui/ozone/platform/dri/gpu_platform_support_host_gbm.cc
@@ -7,6 +7,7 @@
 #include "base/debug/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/dri/channel_observer.h"
 
 namespace ui {
 
@@ -16,6 +17,10 @@ GpuPlatformSupportHostGbm::GpuPlatformSupportHostGbm()
 
 GpuPlatformSupportHostGbm::~GpuPlatformSupportHostGbm() {}
 
+bool GpuPlatformSupportHostGbm::IsConnected() const {
+  return sender_ != NULL;
+}
+
 void GpuPlatformSupportHostGbm::RegisterHandler(
     GpuPlatformSupportHost* handler) {
   handlers_.push_back(handler);
@@ -29,9 +34,24 @@ void GpuPlatformSupportHostGbm::UnregisterHandler(
     handlers_.erase(it);
 }
 
+void GpuPlatformSupportHostGbm::AddChannelObserver(ChannelObserver* observer) {
+  channel_observers_.AddObserver(observer);
+
+  if (sender_)
+    observer->OnChannelEstablished();
+}
+
+void GpuPlatformSupportHostGbm::RemoveChannelObserver(
+    ChannelObserver* observer) {
+  channel_observers_.RemoveObserver(observer);
+}
+
 void GpuPlatformSupportHostGbm::OnChannelEstablished(int host_id,
                                                      IPC::Sender* sender) {
-  TRACE_EVENT0("dri", "GpuPlatformSupportHostGbm::OnChannelEstablished");
+  TRACE_EVENT1("dri",
+               "GpuPlatformSupportHostGbm::OnChannelEstablished",
+               "host_id",
+               host_id);
   host_id_ = host_id;
   sender_ = sender;
 
@@ -42,13 +62,22 @@ void GpuPlatformSupportHostGbm::OnChannelEstablished(int host_id,
 
   for (size_t i = 0; i < handlers_.size(); ++i)
     handlers_[i]->OnChannelEstablished(host_id, sender);
+
+  FOR_EACH_OBSERVER(
+      ChannelObserver, channel_observers_, OnChannelEstablished());
 }
 
 void GpuPlatformSupportHostGbm::OnChannelDestroyed(int host_id) {
-  TRACE_EVENT0("dri", "GpuPlatformSupportHostGbm::OnChannelDestroyed");
+  TRACE_EVENT1("dri",
+               "GpuPlatformSupportHostGbm::OnChannelDestroyed",
+               "host_id",
+               host_id);
   if (host_id_ == host_id) {
     host_id_ = -1;
     sender_ = NULL;
+
+    FOR_EACH_OBSERVER(
+        ChannelObserver, channel_observers_, OnChannelDestroyed());
   }
 
   for (size_t i = 0; i < handlers_.size(); ++i)