Adding support for DOM3 KeyboardEvents Code in KeyboardEvents

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index be369762a4f30d439fe7a48569e884b6694368f9..e2a79fd9194e33042e106613f81630fc1903d3af 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -604,6 +604,18 @@ public:
     // longer notify the listener, if any.
     virtual void stopListening(WebPlatformEventType type) { }
 
+    // This method converts from the supplied DOM code enum to the
+    // embedder's DOM code value for the key pressed. |domCode| values are
+    // based on the value defined in ui/events/keycodes/dom4/keycode_converter_data.h.
+    // Returns null string, if DOM code value is not found.
+    virtual WebString domCodeStringFromEnum(int domCode) { return WebString(); }

[Mike West, 2015/01/29 11:49:35]

"DOM Code String" is ambiguous. Could you rename these to something which makes
it clear that they're key-code related?

[Habib Virji, 2015/01/29 12:24:14]

Will it be okay to rename them DOMKeyboardCodeString? 

This was suggestion which wez suggested. This was kept to keep it consistent
with chromium.

+
+    // This method converts from the suppled DOM code value to the
+    // embedder's DOM code enum for the key pressed. |codeString| is defined in
+    // ui/events/keycodes/dom4/keycode_converter_data.h.
+    // Returns 0, if DOM code enum is not found.
+    virtual int domEnumFromCodeString(const WebString& codeString) { return 0; }

[Mike West, 2015/01/29 11:49:34]

It's a bit strange that we're calling this an enum, when it's completely opaque
to Blink. Blink has an int, and doesn't have any understanding of the enum that
lives at the platform layer.

Can the enum live at the platform layer instead?

[Habib Virji, 2015/01/29 12:24:14]

We went through that discussion
https://codereview.chromium.org/663523002/#msg43, but wez suggested to have it
in chromium side. 

[Rick Byers, 2015/01/29 21:11:10]

Yeah, I thought Wez's arguments for making it opaque to blink were convincing. 
We could call it something other than "enum" if we wanted, but chromium calls it
that so I'm happy to defer to the chromium keyboard experts (eg. Wez) for naming
consistency.

+
     // Quota -----------------------------------------------------------
 
     // Queries the storage partition's storage usage and quota information.