Add PERSISTENT_MAP usage for GpuMemoryBuffers.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index e31b91a053b1a476d75fb948dad0cb711fda65cc..72e2b1cfcdb23311d9cf79f5acf4f22aaebac3c2 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -839,8 +839,14 @@ const char kUseFakeUIForMediaStream[]     = "use-fake-ui-for-media-stream";
 // Enable native GPU memory buffer support when available.
 const char kEnableNativeGpuMemoryBuffers[] = "enable-native-gpu-memory-buffers";
 
-// Overrides the default texture target used with CHROMIUM_image extension.
-const char kUseImageTextureTarget[] = "use-image-texture-target";
+// Overrides the default texture target used with CHROMIUM_image extension for
+// mapable GpuMemoryBuffers.
+const char kMapImageTextureTarget[] = "map-image-texture-target";
+
+// Overrides the default texture target used with CHROMIUM_image extension for
+// persistent-mapable GpuMemoryBuffers.
+const char kPersistentMapImageTextureTarget[] =
+    "persistent-map-image-texture-target";
 
 // Set when Chromium should use a mobile user agent.
 const char kUseMobileUserAgent[] = "use-mobile-user-agent";