cc: Use highp precision for texture coords if available and needed

cc/output/texture_copier.cc

Index: cc/output/texture_copier.cc
diff --git a/cc/output/texture_copier.cc b/cc/output/texture_copier.cc
index a32fb65e58f905ce25089f64ea22f7fa2756662b..1ad0ef0d19e068ed0ed02350620bc7cab828f1cb 100644
--- a/cc/output/texture_copier.cc
+++ b/cc/output/texture_copier.cc
@@ -14,8 +14,11 @@ namespace cc {
 
 AcceleratedTextureCopier::AcceleratedTextureCopier(
     WebKit::WebGraphicsContext3D* context,
-    bool using_bind_uniforms)
-    : context_(context), using_bind_uniforms_(using_bind_uniforms) {
+    bool using_bind_uniforms,
+    int highp_threshold_min)
+    : context_(context)
+    , using_bind_uniforms_(using_bind_uniforms)
+    , highp_threshold_min_(highp_threshold_min) {
   DCHECK(context_);
   GLC(context_, fbo_ = context_->createFramebuffer());
   GLC(context_, position_buffer_ = context_->createBuffer());
@@ -29,12 +32,15 @@ AcceleratedTextureCopier::AcceleratedTextureCopier(
           GL_ARRAY_BUFFER, sizeof(kPositions), kPositions, GL_STATIC_DRAW));
   GLC(context_, context_->bindBuffer(GL_ARRAY_BUFFER, 0));
 
-  blit_program_.reset(new BlitProgram(context_));
+  blit_program_.reset(new BlitProgram(context_, TexCoordPrecisionMedium));
+  blit_program_highp_.reset(new BlitProgram(context_, TexCoordPrecisionHigh));
 }
 
 AcceleratedTextureCopier::~AcceleratedTextureCopier() {
   if (blit_program_)
     blit_program_->Cleanup(context_);
+  if (blit_program_highp_)
+    blit_program_highp_->Cleanup(context_);
   if (position_buffer_)
     GLC(context_, context_->deleteBuffer(position_buffer_));
   if (fbo_)
@@ -72,11 +78,21 @@ void AcceleratedTextureCopier::CopyTexture(Parameters parameters) {
       context_->texParameteri(
           GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));
 
-  if (!blit_program_->initialized())
-    blit_program_->Initialize(context_, using_bind_uniforms_);
-
-  // TODO(danakj): Use EXT_framebuffer_blit if available.
-  GLC(context_, context_->useProgram(blit_program_->program()));
+  TexCoordPrecision texCoordPrecision = TexCoordPrecisionRequired(
+      context_, highp_threshold_min_, parameters.size);
+  if (texCoordPrecision == TexCoordPrecisionHigh) {
+    if (!blit_program_highp_->initialized())
+      blit_program_highp_->Initialize(context_, using_bind_uniforms_);
+
+    // TODO(danakj): Use EXT_framebuffer_blit if available.
+    GLC(context_, context_->useProgram(blit_program_highp_->program()));
+  } else {
+    if (!blit_program_->initialized())
+      blit_program_->Initialize(context_, using_bind_uniforms_);
+
+    // TODO(danakj: Use EXT_framebuffer_blit if available.
+    GLC(context_, context_->useProgram(blit_program_->program()));
+  }
 
   const int kPositionAttribute = 0;
   GLC(context_, context_->bindBuffer(GL_ARRAY_BUFFER, position_buffer_));