Implement the Blink part of the Device Motion API.

Source/Platform/chromium/public/WebDeviceMotionListener.h

Index: Source/Platform/chromium/public/WebDeviceMotionListener.h
diff --git a/Source/Platform/chromium/public/WebDeviceMotionListener.h b/Source/Platform/chromium/public/WebDeviceMotionListener.h
new file mode 100644
index 0000000000000000000000000000000000000000..2d3111243e38e13473ffe6e9352cb6e0170a942c
--- /dev/null
+++ b/Source/Platform/chromium/public/WebDeviceMotionListener.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef WebDeviceMotionListener_h
+#define WebDeviceMotionListener_h
+
+namespace WebKit {
+
+class WebDeviceMotionData;
+
+class WebDeviceMotionListener {
+public:
+    // This method is called every time new device motion data is available.
+    virtual void didChangeDeviceMotion(const WebDeviceMotionData&) = 0;
+
+    // Sets a listener to propagate to when didChangeDeviceMotion is called.
+    virtual void setListener(WebDeviceMotionListener*) = 0;

[darin (slow to review), 2013/05/23 06:41:56]

This also seems wrong.  The point of WebDeviceMotionListener is to provide the
Platform implementation with a way to feed new WebDeviceMotionData objects to
Blink.  It doesn't make sense for the Platform layer to call back into Blink to
cause Blink to redirect WebDeviceMotionData objects elsewhere.  The Platform
layer should just do that directly, avoiding the call to didChangeDeviceMotion
entirely.

Platform says: "Hey, that thing I just gave you, actually, I take it back,
please send it elsewhere."
Blink says: "Wait, if you don't want me to have it, then why did you give it to
me in the first place?"

[timvolodine, 2013/05/23 11:39:27]

I probably misunderstood one of your previous comments regarding 'chaining' of
listeners. Apologies if that is the case.
Let's address the testing in a separate CL if you don't mind. I've removed the
test-related code from this CL for now.

In general it looks like there is no very proper way of platform-based testing
in this case since TestRunner uses the 'real' platform
renderer_webkitsupport_impl, while ideally it should be a mock.

+};
+
+} // namespace WebKit
+
+#endif // WebDeviceMotionListener_h