Fix deadlock of WebViewCoreThread

There was a deadlock in destroy process.
Investigation showed that WebViewCoreThread is waiting some
callbacks but in this case WebViewCoreThread can not resume
itself not to call notify method.

Flow:
1. CallbackProxy.sendMessageToUiThreadSync
2. WebViewClassic.destroy()
3. CallbackProxy.blockMessages()
4. CallbackProxy.handleMessage is called via MainThread
5. The WebViewCoreThread deadlock is occured.

The cases we have to call notify method are followings.
OVERRIDE_URL
CREATE_WINDOW
SAVE_PASSWORD
NOTIFY
OPEN_FILE_CHOOSER
JS_ALERT
JS_CONFIRM
JS_PROMPT
JS_UNLOAD
JS_TIMEOUT

Change-Id: I9d95ae500bf6338d77b32b5fa15de7cff5720d0f
Fix graphical artifact in the fisheye effect

The fisheye effect generates a graphical artifact close to the center of
the picture, due to bad precision and division by zero in the shader.
The problem is fixed by making a small change in the shader, so that the
picture is uniformly scaled close to the center instead. This avoids the
problem and looks as expected, without affecting the performance.

Change-Id: I063f60facd30708db29ff544fdb47ac896e3d54b
Revert "gps: fixed singleshot session that doesn't stop"

This reverts commit 0b43a71311a1f78b078551fa0ef4f607a24f8744.