viz: Use texture clamping shader always

https://chromium-review.googlesource.com/c/chromium/src/+/883944
restricted how often we would use shaders that clamped tex coords.
However, this confusingly regressed perf a little bit on Android,
which implies that program switching is expensive.

This patch changes GLRenderer to always texture clamp these quads
which reduces the number of shaders we use.

Bug: 806836,806826
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I2b2e71b362d6a12f17758abe2edddf1759536016
Reviewed-on: https://chromium-review.googlesource.com/972546Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Commit-Queue: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547780}

components/viz/service/display/gl_renderer.cc

@@ -1949,15 +1949,18 @@ void GLRenderer::DrawContentQuadNoAA(const ContentDrawQuadBase* quad,
       !quad->IsRightEdge() || texture_size.width() == tex_coord_rect.right();
   bool fills_bottom_edge =
       !quad->IsBottomEdge() || texture_size.height() == tex_coord_rect.bottom();
-  bool has_tex_clamp_rect =
-      filter == GL_LINEAR && (!fills_right_edge || !fills_bottom_edge);
+  bool has_tex_clamp_rect = true;
   gfx::SizeF tex_clamp_size(texture_size);
   // Clamp from the original tex coord rect, instead of the one that has
-  // been adjusted by the visible rect.
-  if (!fills_right_edge)
-    tex_clamp_size.set_width(quad->tex_coord_rect.right() - 0.5f);
-  if (!fills_bottom_edge)
-    tex_clamp_size.set_height(quad->tex_coord_rect.bottom() - 0.5f);
+  // been adjusted by the visible rect.  Nearest neighbor should never be
+  // clamped.  However, still specify a tex clamp rect so that we don't
+  // thrash shaders.
+  if (filter == GL_LINEAR) {
+    if (!fills_right_edge)
+      tex_clamp_size.set_width(quad->tex_coord_rect.right() - 0.5f);
+    if (!fills_bottom_edge)
+      tex_clamp_size.set_height(quad->tex_coord_rect.bottom() - 0.5f);
+  }
 
   // Map to normalized texture coordinates.
   if (sampler != SAMPLER_TYPE_2D_RECT) {

content/test/gpu/gpu_tests/pixel_expectations.py

@@ -111,3 +111,17 @@ class PixelExpectations(GpuTestExpectations):
               ['linux', 'mac', 'win'], bug=744658)
     self.Fail('Pixel_CSS3DBlueBox_NoGpuProcess',
               ['linux', 'mac', 'win'], bug=744658)
+
+    # TODO(enne): temporarily suppress these tests until rebaselined.
+    self.Fail('Pixel_2DCanvasWebGL', ['android'], bug=972546)
+    self.Fail('Pixel_Canvas2DRedBox', ['android'], bug=972546)
+    self.Fail('Pixel_CanvasDisplayLinearRGBAccelerated2D',
+              ['android'], bug=972546)
+    self.Fail('Pixel_CanvasDisplayLinearRGBUnaccelerated2DGPUCompositing',
+              ['android'], bug=972546)
+    self.Fail('Pixel_WebGLGreenTriangle_AA_Alpha', ['android'], bug=972546)
+    self.Fail('Pixel_WebGLGreenTriangle_AA_NoAlpha', ['android'], bug=972546)
+    self.Fail('Pixel_WebGLGreenTriangle_NoAA_Alpha', ['android'], bug=972546)
+    self.Fail('Pixel_WebGLGreenTriangle_NoAA_NoAlpha', ['android'], bug=972546)
+    self.Fail('Pixel_WebGLTransparentGreenTriangle_NoAlpha_ImplicitClear',
+              ['android'], bug=972546)