gpu: support immutable texture on Linux Mesa driver and GLES3.

Mesa GL driver supports GL_ARB_texture_storage extensions, not
GL_EXT_texture_storage. GLES3 supports glTexStroage2D by default.

GLES3 doesn't support BGRA format for immutable texture without
GL_APPLE_texture_format_bgra8888 extension. We prefer BGRA support
to immutable texture support, so GLES3 enables immutable texture
only if it supports GL_APPLE_texture_format_bgra8888.

In addition, currently the compositor blindly uses BGRA on glTexStorage2D.
It can cause a potential bug so this CL checks BGRA format support
to use BGRA on glTexStorage2D.

This CL makes Intel GPU (e.g. Intel Chromebook) and GLES3 devices with
GL_APPLE_texture_format_bgra8888 extension take advantage of immutable
texture.

BUG=407034

Review URL: https://codereview.chromium.org/499283002

Cr-Commit-Position: refs/heads/master@{#292175}

1 files changed, 3 insertions, 0 deletions

diff --git a/cc/test/test_web_graphics_context_3d.h b/cc/test/test_web_graphics_context_3d.h
index a7d5e0b..e33c07a 100644
--- a/cc/test/test_web_graphics_context_3d.h
+++ b/cc/test/test_web_graphics_context_3d.h
@@ -304,6 +304,9 @@ class TestWebGraphicsContext3D {
   void set_support_compressed_texture_etc1(bool support) {
     test_capabilities_.gpu.texture_format_etc1 = support;
   }
+  void set_support_texture_format_bgra8888(bool support) {
+    test_capabilities_.gpu.texture_format_bgra8888 = support;
+  }
   void set_support_texture_storage(bool support) {
     test_capabilities_.gpu.texture_storage = support;
   }