Add initial support for NV_path_rendering extension to gpu command buffer

Add initial support for NV_path_rendering extension to gpu command
buffer. This is needed in order to support NV_path_rendering
implementation in Skia.

Implement this by creating a new GL ES pseudo-extension called
CHROMIUM_path_rendering. The CHROMIUM_path_rendering extension
will be exposed to clients only if the context is not a webgl context,
NV_path_rendering extension is present. Also, EXT_direct_state_access
extension must be present for Open GL.

Add matrix functions needed to support the feature:

void glMatrixLoadfEXT(GLenum matrixMode, const GLfloat* m)
void glMatrixLoadIdentityEXT(GLenum matrixMode)

NV_path_rendering needs these functions to implement transformations
for the path drawing.

Changes the build_gles2_cmd_buffer.py to be able to generate context
state variables that are arrays. The state variable is defined to be an
an array when its default value is an array.

Changes the build_gles2_cmd_buffer.py to round the float GL state
variables with round() when querying them with GetInteger.

The values GL_*_CHROMIUM tokens added match the values of corresponding
GL_*_NV tokens from the NV_path_rendering extensions. This is why the
values are passed after validation to the receiving GL function, without
any mapping.

BUG=344330

Review URL: https://codereview.chromium.org/169603002

Cr-Commit-Position: refs/heads/master@{#291878}

4 files changed, 87 insertions, 0 deletions

diff --git a/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_path_rendering.txt b/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_path_rendering.txt
new file mode 100644
index 0000000..d2e8c93
--- /dev/null
+++ b/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_path_rendering.txt
@@ -0,0 +1,65 @@
+Name
+
+    CHROMIUM_path_rendering
+
+Name Strings
+
+    GL_CHROMIUM_path_rendering
+
+Version
+
+    Last Modifed Date: August 14, 2014
+
+Dependencies
+
+    OpenGL ES 3.0 is required.
+
+Overview
+
+    This extensions implements path rendering using
+    OpenGL API.
+
+New Tokens
+
+    Accepted by the <matrixMode> parameter of MatrixLoadfCHROMIUM and
+    MatrixLoadIdentityCHROMIUM:
+    PATH_MODELVIEW_CHROMIUM                           0x1700
+    PATH_PROJECTION_CHROMIUM                          0x1701
+
+    Accepted by the <pname> parameter of GetIntegerv,
+    GetFloatv:
+    PATH_MODELVIEW_MATRIX_CHROMIUM                    0x0BA6
+    PATH_PROJECTION_MATRIX_CHROMIUM                   0x0BA7
+
+
+New Procedures and Functions
+
+    void MatrixLoadfCHROMIUM(enum matrixMode, float* matrix)
+
+    Takes a pointer to a 4x4 matrix stored in column-major order as 16
+    consecutive floating-point values. The matrixMode specifies which
+    matrix, PATH_MODELVIEW_CHROMIUM or PATH_PROJECTION_CHROMIUM is used.
+
+    The funcition specifies either modelview or projection matrix
+    to be used with path rendering API calls.
+
+    void MatrixLoadIdentityCHROMIUM(enum matrixMode)
+
+    Effectively calls MatrixLoadf with the identity matrix.
+
+Errors
+
+    None.
+
+New State
+
+    Get Value                       Type   Get Command  Initial  Description
+    -----------------------------  -----  ------------ -------- -------------------
+    PATH_MODELVIEW_MATRIX_CHROMIUM  16xR   GetFloatv    all 0's  Current modelview
+                                                                 matrix for path rendering
+    PATH_PROJECTION_MATRIX_CHROMIUM 16xR   GetFloatv    all 0's  Current projection
+                                                                 matrix for path rendering
+
+Revision History
+
+    14/8/2014    Documented the extension
diff --git a/gpu/GLES2/gl2chromium.h b/gpu/GLES2/gl2chromium.h
index 42889dd..0dc648d 100644
--- a/gpu/GLES2/gl2chromium.h
+++ b/gpu/GLES2/gl2chromium.h
@@ -10,6 +10,10 @@
 #include <GLES2/gl2platform.h>
 
 #define GL_CONTEXT_LOST 0x300E
+#define GL_PATH_MODELVIEW_CHROMIUM 0x1700
+#define GL_PATH_PROJECTION_CHROMIUM 0x1701
+#define GL_PATH_MODELVIEW_MATRIX_CHROMIUM 0x0BA6
+#define GL_PATH_PROJECTION_MATRIX_CHROMIUM 0x0BA7
 
 #if defined(GLES2_USE_MOJO)
 #define GLES2_GET_FUN(name) MojoGLES2gl ## name
diff --git a/gpu/GLES2/gl2chromium_autogen.h b/gpu/GLES2/gl2chromium_autogen.h
index 7f3bbee..e71c0f7 100644
--- a/gpu/GLES2/gl2chromium_autogen.h
+++ b/gpu/GLES2/gl2chromium_autogen.h
@@ -239,5 +239,7 @@
 #define glDiscardBackbufferCHROMIUM GLES2_GET_FUN(DiscardBackbufferCHROMIUM)
 #define glScheduleOverlayPlaneCHROMIUM \
   GLES2_GET_FUN(ScheduleOverlayPlaneCHROMIUM)
+#define glMatrixLoadfCHROMIUM GLES2_GET_FUN(MatrixLoadfCHROMIUM)
+#define glMatrixLoadIdentityCHROMIUM GLES2_GET_FUN(MatrixLoadIdentityCHROMIUM)
 
 #endif  // GPU_GLES2_GL2CHROMIUM_AUTOGEN_H_
diff --git a/gpu/GLES2/gl2extchromium.h b/gpu/GLES2/gl2extchromium.h
index 0671187..b5ab0cb 100644
--- a/gpu/GLES2/gl2extchromium.h
+++ b/gpu/GLES2/gl2extchromium.h
@@ -717,6 +717,22 @@ typedef void(GL_APIENTRYP PFNGLSCHEDULEOVERLAYPLANECHROMIUMPROC)(
 #endif
 #endif  /* GL_CHROMIUM_sync_query */
 
+#ifndef GL_CHROMIUM_path_rendering
+#define GL_CHROMIUM_path_rendering 1
+
+#ifdef GL_GLEXT_PROTOTYPES
+GL_APICALL void GL_APIENTRY
+    glMatrixLoadfCHROMIUM(GLenum mode, const GLfloat* m);
+GL_APICALL void GL_APIENTRY glMatrixLoadIdentityCHROMIUM(GLenum mode);
+#endif
+
+typedef void(GL_APIENTRYP PFNGLMATRIXLOADFCHROMIUMPROC)(GLenum matrixMode,
+                                                        const GLfloat* m);
+typedef void(GL_APIENTRYP PFNGLMATRIXLOADIDENTITYCHROMIUMPROC)(
+    GLenum matrixMode);
+
+#endif /* GL_CHROMIUM_path_rendering */
+
 #ifdef __cplusplus
 }
 #endif