Make unprefixed EME APIs use platform and Chromium.

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index acff9862dc1663b4f3cc6a0b73606bc332a52457..5b02828cb4a1bcd9cc865d4f8fb7f08095f437dd 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -51,6 +51,7 @@ namespace WebKit {
 
 class WebAudioBus;
 class WebBlobRegistry;
+class WebCDM;
 class WebClipboard;
 class WebCompositorSupport;
 class WebCookieJar;
@@ -143,6 +144,8 @@ public:
     virtual WebAudioDevice* createAudioDevice(size_t bufferSize, unsigned numberOfChannels, double sampleRate, WebAudioDevice::RenderCallback*) { return 0; }
     virtual WebAudioDevice* createAudioDevice(size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfChannels, double sampleRate, WebAudioDevice::RenderCallback*) { return 0; }
 
+    // May return null.
+    virtual WebCDM* createCDM(const WebString& keySystem) { return 0; }
 
     // Blob ----------------------------------------------------------------