[chromium] Always pre-reserve scrollbar and scroll corner textures

[chromium] Always pre-reserve scrollbar and scroll corner textures
https://bugs.webkit.org/show_bug.cgi?id=77251

Reviewed by James Robinson.

Source/WebCore:

Add a flag to LayerChromium that says that a layer's textures should
always be reserved. Prior to painting layers, find all layers marked
as such and reserve their textures. This will prevent texture memory
limits from being hit before the root layer's scrollbars are reserved
and painted.

* platform/graphics/chromium/LayerChromium.cpp:
(WebCore::LayerChromium::LayerChromium):
* platform/graphics/chromium/LayerChromium.h:
(LayerChromium):
(WebCore::LayerChromium::reserveTextures):
(WebCore::LayerChromium::setAlwaysReserveTextures):
(WebCore::LayerChromium::alwaysReserveTextures):
* platform/graphics/chromium/TiledLayerChromium.cpp:
(WebCore::TiledLayerChromium::reserveTextures):
* platform/graphics/chromium/TiledLayerChromium.h:
():
* platform/graphics/chromium/cc/CCLayerTreeHost.cpp:
(WebCore::CCLayerTreeHost::updateLayers):
(WebCore::CCLayerTreeHost::reserveTextures):
(WebCore):
* platform/graphics/chromium/cc/CCLayerTreeHost.h:
():

Source/WebKit/chromium:

* src/NonCompositedContentHost.cpp:
(WebKit::reserveScrollbarLayers):
(WebKit):
(WebKit::NonCompositedContentHost::setViewport):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@106289 268f45cc-cd09-0410-ab3c-d52691b4dbfc