Add texture filtering precision hint

A new extension will be added to SwiftShader in order to allow
Chromium to trigger high precision filtering when necessary.
This extension is documented in:
extensions/CHROMIUM_texture_filtering_hint.txt

Bug swiftshader:76

Change-Id: I7c5b5c5fd01afbd7079e7949ecbd9c18fc539f2b
Reviewed-on: https://swiftshader-review.googlesource.com/10708
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
diff --git a/src/Renderer/PixelProcessor.cpp b/src/Renderer/PixelProcessor.cpp
index 172e8ef..db11aed 100644
--- a/src/Renderer/PixelProcessor.cpp
+++ b/src/Renderer/PixelProcessor.cpp
@@ -444,6 +444,15 @@
 		else ASSERT(false);
 	}
 
+	void PixelProcessor::setHighPrecisionFiltering(unsigned int sampler, bool highPrecisionFiltering)
+	{
+		if(sampler < TEXTURE_IMAGE_UNITS)
+		{
+			context->sampler[sampler].setHighPrecisionFiltering(highPrecisionFiltering);
+		}
+		else ASSERT(false);
+	}
+
 	void PixelProcessor::setSwizzleR(unsigned int sampler, SwizzleType swizzleR)
 	{
 		if(sampler < TEXTURE_IMAGE_UNITS)