Cache GL's viewport on the GPU command buffer client side.

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 0f12cd4c93d2c81f807d469a9a670f165c6b5f50..eaf44d0c5e83d6d5063bb69f88123d97fe8a6c95 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -804,6 +804,10 @@ bool GLES2Implementation::GetHelper(GLenum pname, GLint* params) {
     case GL_MAX_VERTEX_UNIFORM_VECTORS:
       *params = capabilities_.max_vertex_uniform_vectors;
       return true;
+    case GL_MAX_VIEWPORT_DIMS:
+      params[0] = capabilities_.max_viewport_width;
+      params[1] = capabilities_.max_viewport_height;
+      return true;
     case GL_NUM_COMPRESSED_TEXTURE_FORMATS:
       *params = capabilities_.num_compressed_texture_formats;
       return true;
@@ -847,6 +851,20 @@ bool GLES2Implementation::GetHelper(GLenum pname, GLint* params) {
       *params = static_cast<GLint>(query_tracker_->CheckAndResetDisjoint());
       return true;
 
+    case GL_VIEWPORT:
+      if (state_.viewport_width > 0 || state_.viewport_height > 0) {
+        params[0] = state_.viewport_x;
+        params[1] = state_.viewport_y;
+        params[2] = std::min(state_.viewport_width,
+                             capabilities_.max_viewport_width);
+        params[3] = std::min(state_.viewport_height,
+                             capabilities_.max_viewport_height);
+        return true;
+      }
+      // If they haven't been cached on the client side, go to service side
+      // to query the underlying driver.
+      return false;
+
     // Non-cached parameters.
     case GL_ALIASED_LINE_WIDTH_RANGE:
     case GL_ALIASED_POINT_SIZE_RANGE:
@@ -879,7 +897,6 @@ bool GLES2Implementation::GetHelper(GLenum pname, GLint* params) {
     case GL_IMPLEMENTATION_COLOR_READ_FORMAT:
     case GL_IMPLEMENTATION_COLOR_READ_TYPE:
     case GL_LINE_WIDTH:
-    case GL_MAX_VIEWPORT_DIMS:
     case GL_PACK_ALIGNMENT:
     case GL_POLYGON_OFFSET_FACTOR:
     case GL_POLYGON_OFFSET_FILL:
@@ -914,7 +931,6 @@ bool GLES2Implementation::GetHelper(GLenum pname, GLint* params) {
     case GL_STENCIL_WRITEMASK:
     case GL_SUBPIXEL_BITS:
     case GL_UNPACK_ALIGNMENT:
-    case GL_VIEWPORT:
       return false;
     default:
       break;
@@ -7030,6 +7046,22 @@ void GLES2Implementation::InvalidateCachedExtensions() {
   cached_extensions_.clear();
 }
 
+void GLES2Implementation::Viewport(GLint x,
+                                   GLint y,
+                                   GLsizei width,
+                                   GLsizei height) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glViewport(" << x << ", " << y
+                     << ", " << width << ", " << height << ")");
+  if (width < 0 || height < 0) {
+    SetGLError(GL_INVALID_VALUE, "glViewport", "negative width/height");
+    return;
+  }
+  state_.SetViewport(x, y, width, height);
+  helper_->Viewport(x, y, width, height);
+  CheckGLError();
+}
+
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.