Convert AwViewHostMsg_UpdateHitTestData to Mojo

This CL migrates AwViewHostMsg_UpdateHitTestData IPC
message to LocalMainFrameHost interface because the
IPC message has been used by 2 functions. So, this CL
adds the message to LocalMainFrameHost interface instead
of handling it as a reply callback.

To support the parameter, this CL moves AwHitTestData
struct and HitTestDataType enum to Mojo.

 - AwHitTestData -> android_webview::mojom::HitTestData
 - Type -> android_webview::mojom::HitTestDataType

Then, all uses of the native struct and enum are replaced
by the Mojo struct and type.

Bug: 1146495
Change-Id: I906e00f1f5f3e18556613b39eedb90bf845b164c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2574560
Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#836303}