ozone: Allow loading the platform implementation from a system library.

ui/ozone/ozone_platform.cc

Index: ui/ozone/ozone_platform.cc
diff --git a/ui/ozone/ozone_platform.cc b/ui/ozone/ozone_platform.cc
index e8199b2ce93f86846235f73b8459b9f650859d5f..7bfa1fd167013d8d6517fad60ca0ac6e0dfb9cd4 100644
--- a/ui/ozone/ozone_platform.cc
+++ b/ui/ozone/ozone_platform.cc
@@ -5,6 +5,9 @@
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
+#include "base/scoped_native_library.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/threading/thread_restrictions.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"
@@ -20,11 +23,37 @@ namespace {
 // Helper to construct an OzonePlatform by name using the platform list.
 OzonePlatform* CreatePlatform(const std::string& platform_name) {
   // Search for a matching platform in the list.
-  for (int i = 0; i < kOzonePlatformCount; ++i)
+  for (int i = 0; i < kOzonePlatformCount; ++i) {
     if (platform_name == kOzonePlatforms[i].name)
       return kOzonePlatforms[i].constructor();
-
-  LOG(FATAL) << "Invalid ozone platform: " << platform_name;
+  }
+
+  // Try to load the module for the paltform.
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
+  base::NativeLibraryLoadError load_error;
+  base::string16 platform_module_path =
+      base::GetNativeLibraryName(base::ASCIIToUTF16(platform_name));
+  const char kPlatformConstructor[] = "CreateOzonePlatform";
+  base::NativeLibrary platform_module = base::LoadNativeLibrary(
+      base::FilePath(base::UTF16ToASCII(platform_module_path)), &load_error);
+  if (!platform_module) {
+    LOG(FATAL) << "Failed to load library (error: " << load_error.ToString()
+               << ")";
+  } else {
+    OzonePlatformConstructor platform_constructor =
+        reinterpret_cast<OzonePlatformConstructor>(
+            base::GetFunctionPointerFromNativeLibrary(platform_module,
+                                                      kPlatformConstructor));
+    if (platform_constructor) {
+      return platform_constructor();
+    } else {
+      LOG(FATAL) << "Module " << platform_module_path
+                 << " does not have the constructor function ("
+                 << kPlatformConstructor << ") to initialize the platform.";
+    }
+  }
+
+  NOTREACHED();
   return NULL;  // not reached
 }