ozone: Initialize a subsystem only if necessary.

ui/ozone/ozone_platform.cc

 // Copyright 2013 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.
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "ui/base/cursor/ozone/cursor_factory_ozone.h"
 #include "ui/events/ozone/event_factory_ozone.h"
 #include "ui/gfx/ozone/surface_factory_ozone.h"
 #include "ui/ozone/ime/input_method_context_factory_ozone.h"
 #include "ui/ozone/ozone_platform.h"
 #include "ui/ozone/ozone_platform_list.h"
 #include "ui/ozone/ozone_switches.h"
 
 namespace ui {
 
 namespace {
 
 // Helper to construct an OzonePlatform by name using the platform list.
-OzonePlatform* CreatePlatform(const std::string& platform_name) {
+OzonePlatform* CreatePlatform(const std::string& platform_name,
+                              bool for_gpu) {
   // Search for a matching platform in the list.
   for (int i = 0; i < kOzonePlatformCount; ++i)
-    if (platform_name == kOzonePlatforms[i].name)
-      return kOzonePlatforms[i].constructor();
+    if (platform_name == kOzonePlatforms[i].name) {
+      return for_gpu ? kOzonePlatforms[i].ConstructorForGPU()
+                     : kOzonePlatforms[i].ConstructorForUI();
+    }
 
   LOG(FATAL) << "Invalid ozone platform: " << platform_name;
   return NULL;  // not reached
 }
 
 // Returns the name of the platform to use (value of --ozone-platform flag).
 std::string GetPlatformName() {
   // The first platform is the default.
   if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kOzonePlatform) &&
       kOzonePlatformCount > 0)
     return kOzonePlatforms[0].name;
   return CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
       switches::kOzonePlatform);
 }
 
 }  // namespace
 
-OzonePlatform::OzonePlatform() {}
+OzonePlatform::OzonePlatform() {
+  CHECK(!instance_) << "There should only be a single OzonePlatform.";
+  instance_ = this;
+}
 
 OzonePlatform::~OzonePlatform() {
-  gfx::SurfaceFactoryOzone::SetInstance(NULL);
-  ui::EventFactoryOzone::SetInstance(NULL);
-  ui::CursorFactoryOzone::SetInstance(NULL);
+  CHECK_EQ(instance_, this);
+  instance_ = NULL;
 }
 
 // static
-void OzonePlatform::Initialize() {
+void OzonePlatform::InitializeForUI() {
   if (instance_)
     return;
 
   std::string platform = GetPlatformName();
-
-  TRACE_EVENT1("ozone", "OzonePlatform::Initialize", "platform", platform);
-
-  instance_ = CreatePlatform(platform);
-
-  // Inject ozone interfaces.
-  gfx::SurfaceFactoryOzone::SetInstance(instance_->GetSurfaceFactoryOzone());
-  ui::EventFactoryOzone::SetInstance(instance_->GetEventFactoryOzone());
+  TRACE_EVENT1("ozone", "OzonePlatform::InitializeForUI", "platform", platform);
+  CreatePlatform(platform, false);
   ui::InputMethodContextFactoryOzone::SetInstance(

[kalyank, 2014/05/15 19:21:45]

shouldn't we do the same with this. It should be set only in case of UI ?

[sadrul, 2014/05/15 19:27:24]

I wanted to, but the SetInstance() here is for the non-ozone
LinuxInputMethodContextFactory. So I left that alone for the moment. I do want
to revisit this soon though (I am not convinced we actually need the
InputMethodContextFactoryOzone at all. The ozone platforms should just
create/set a LinuxInputMethodContextFactory instance, and that should be
sufficient).

       instance_->GetInputMethodContextFactoryOzone());
-  ui::CursorFactoryOzone::SetInstance(instance_->GetCursorFactoryOzone());
 }
 
 // static
+void OzonePlatform::InitializeForGPU() {
+  if (instance_)
+    return;
+
+  std::string platform = GetPlatformName();
+  TRACE_EVENT1("ozone", "OzonePlatform::InitializeForGPU",
+               "platform", platform);
+  CreatePlatform(platform, true);
+}
+
+// static
 OzonePlatform* OzonePlatform::GetInstance() {
   CHECK(instance_) << "OzonePlatform is not initialized";
   return instance_;
 }
 
 // static
 OzonePlatform* OzonePlatform::instance_;
 
 }  // namespace ui