Android WebView: fix missing an invalidate

When webview translates into the screen from offscreen by calling
WebView#SetTranslateX/Y, onDrawHardware is called with an empty global
visible rect.
When the webview is still offscreen, Android frameworks won't call
DrawGL on WebView, which means the "parent draw constraints" stored in
hardware renderer won't contain the draw constraints when the webview is
offscreen.
When webview gets an ondraw with an empty global visible rect, we need
to make sure the parent draw constraints of the corresponding DrawGL is
always posted back to child compositor and triggers an invalidate.

BUG=417479

Review URL: https://codereview.chromium.org/603633003

Cr-Commit-Position: refs/heads/master@{#296589}
4 files changed