sRGB support in Ganesh. Several pieces:

src/gpu/gl/GrGLGpu.cpp

Index: src/gpu/gl/GrGLGpu.cpp
diff --git a/src/gpu/gl/GrGLGpu.cpp b/src/gpu/gl/GrGLGpu.cpp
index 76cb1a068a2bc3dee7ae2df28bc167d1eda2aad9..62baf7900283a90101d5607acd5ccad86d688d09 100644
--- a/src/gpu/gl/GrGLGpu.cpp
+++ b/src/gpu/gl/GrGLGpu.cpp
@@ -898,6 +898,7 @@ static inline GrGLint config_alignment(GrPixelConfig config) {
         case kRGBA_8888_GrPixelConfig:
         case kBGRA_8888_GrPixelConfig:
         case kSRGBA_8888_GrPixelConfig:
+        case kSBGRA_8888_GrPixelConfig:
         case kRGBA_float_GrPixelConfig:
             return 4;
         default:
@@ -2100,13 +2101,15 @@ bool GrGLGpu::flushGLState(const GrPipeline& pipeline, const GrPrimitiveProcesso
     SkSTArray<8, const GrTextureAccess*> textureAccesses;
     program->setData(primProc, pipeline, &textureAccesses);
 
+    GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(pipeline.getRenderTarget());
+    bool allowSRGB = GrAllowSRGBForDestinationPixelConfig(glRT->config());
+
     int numTextureAccesses = textureAccesses.count();
     for (int i = 0; i < numTextureAccesses; i++) {
-        this->bindTexture(i, textureAccesses[i]->getParams(),
+        this->bindTexture(i, textureAccesses[i]->getParams(), allowSRGB,
                           static_cast<GrGLTexture*>(textureAccesses[i]->getTexture()));
     }
 
-    GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(pipeline.getRenderTarget());
     this->flushStencil(pipeline.getStencil());
     this->flushScissor(pipeline.getScissorState(), glRT->getViewport(), glRT->origin());
     this->flushHWAAState(glRT, pipeline.isHWAntialiasState(), !pipeline.getStencil().isDisabled());
@@ -2607,6 +2610,16 @@ bool GrGLGpu::onGetReadPixelsInfo(GrSurface* srcSurface, int width, int height,
             tempDrawInfo->fSwizzle = GrSwizzle::BGRA();
             tempDrawInfo->fReadConfig = kRGBA_8888_GrPixelConfig;
             ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
+        } else if (readConfig == kSBGRA_8888_GrPixelConfig &&
+            this->glCaps().isConfigRenderable(kSRGBA_8888_GrPixelConfig, false) &&
+            this->readPixelsSupported(kSRGBA_8888_GrPixelConfig, kSRGBA_8888_GrPixelConfig)) {
+            // We're trying to read sBGRA but it's not supported. If sRGBA is renderable and
+            // we can read it back, then do a swizzling draw to a sRGBA and read it back (which
+            // will effectively be sBGRA).
+            tempDrawInfo->fTempSurfaceDesc.fConfig = kSRGBA_8888_GrPixelConfig;
+            tempDrawInfo->fSwizzle = GrSwizzle::BGRA();
+            tempDrawInfo->fReadConfig = kSRGBA_8888_GrPixelConfig;
+            ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
         } else if (readConfig == kAlpha_8_GrPixelConfig) {
             // onReadPixels implements a fallback for cases where we are want to read kAlpha_8,
             // it's unsupported, but 32bit RGBA reads are supported.
@@ -3311,7 +3324,8 @@ static void get_tex_param_swizzle(GrPixelConfig config,
     }
 }
 
-void GrGLGpu::bindTexture(int unitIdx, const GrTextureParams& params, GrGLTexture* texture) {
+void GrGLGpu::bindTexture(int unitIdx, const GrTextureParams& params, bool dstConfigAllowsSRGB,
+                          GrGLTexture* texture) {
     SkASSERT(texture);
 
 #ifdef SK_DEBUG
@@ -3347,6 +3361,19 @@ void GrGLGpu::bindTexture(int unitIdx, const GrTextureParams& params, GrGLTextur
     bool setAll = timestamp < this->getResetTimestamp();
     GrGLTexture::TexParams newTexParams;
 
+    if (this->caps()->srgbSupport()) {
+        // By default, the decision to allow SRGB decode is based on the destination config.
+        // A texture can override that by specifying a value in GrTextureParams.
+        newTexParams.fSRGBDecode =
+            (dstConfigAllowsSRGB || GrTextureParams::kForceAllowSRGB_SRGBMode == params.srgbMode())
+            ? GR_GL_DECODE_EXT : GR_GL_SKIP_DECODE_EXT;
+
+        if (setAll || newTexParams.fSRGBDecode != oldTexParams.fSRGBDecode) {
+            this->setTextureUnit(unitIdx);
+            GL_CALL(TexParameteri(target, GR_GL_TEXTURE_SRGB_DECODE_EXT, newTexParams.fSRGBDecode));
+        }
+    }
+
     static GrGLenum glMinFilterModes[] = {
         GR_GL_NEAREST,
         GR_GL_LINEAR,
@@ -4014,7 +4041,7 @@ void GrGLGpu::copySurfaceAsDraw(GrSurface* dst,
 
     GrGLTexture* srcTex = static_cast<GrGLTexture*>(src->asTexture());
     GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kNone_FilterMode);
-    this->bindTexture(0, params, srcTex);
+    this->bindTexture(0, params, true, srcTex);
 
     GrGLIRect dstVP;
     this->bindSurfaceFBOForCopy(dst, GR_GL_FRAMEBUFFER, &dstVP, kDst_TempFBOTarget);