Implement GL_CHROMIUM_rate_limit_offscreen_context

+jamesr for OWNERS on content/renderer because nobody else on GPU has owners there. :s

BUG=81481

Review URL: http://codereview.chromium.org/6976012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@85233 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 45 insertions, 2 deletions

diff --git a/gpu/GLES2/gl2ext.h b/gpu/GLES2/gl2ext.h
index d9d64e0..8738f82 100644
--- a/gpu/GLES2/gl2ext.h
+++ b/gpu/GLES2/gl2ext.h
@@ -971,9 +971,27 @@ typedef void (GL_APIENTRYP PFNGLWaitLATCHCHROMIUM) (GLuint latch_id);
 #endif
 #endif
 
+/* GL_CHROMIUM_rate_limit_offscreen_context */
+/*
+ * This extension will block if the calling context has gotten more than two
+ * glRateLimit calls ahead of the GPU process. This keeps the client in sync
+ * with the GPU without having to call swapbuffers, which has potentially
+ * undesirable side effects.
+ */
+#ifndef GL_CHROMIUM_rate_limit_offscreen_context
+#define GL_CHROMIUM_rate_limit_offscreen_context 1
+#ifdef GL_GLEXT_PROTOTYPES
+#define glRateLimitOffscreenContextCHROMIUM  GLES2_GET_FUN(RateLimitOffscreenContextCHROMIUM)
+#if !defined(GLES2_USE_CPP_BINDINGS)
+GL_APICALL void GL_APIENTRY glRateLimitOffscreenContextCHROMIUM (void);
+#endif
+#else
+typedef void (GL_APIENTRYP PFNGLRATELIMITOFFSCREENCONTEXTCHROMIUM) ();
+#endif
+#endif
+
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* __gl2ext_h_ */
-
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index a955e00..cf36ade 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -213,6 +213,7 @@ GL_APICALL const GLchar* GL_APIENTRY glGetRequestableExtensionsCHROMIUM (void);
 GL_APICALL void         GL_APIENTRY glRequestExtensionCHROMIUM (const char* extension);
 GL_APICALL void         GL_APIENTRY glSetLatchCHROMIUM (GLuint latch_id);
 GL_APICALL void         GL_APIENTRY glWaitLatchCHROMIUM (GLuint latch_id);
+GL_APICALL void         GL_APIENTRY glRateLimitOffscreenContextCHROMIUM (void);
 """
 
 # This is the list of all commmands that will be generated and their Id.
@@ -1694,6 +1695,11 @@ _FUNCTION_INFO = {
   'WaitLatchCHROMIUM': {
     'type': 'Custom',
   },
+  'RateLimitOffscreenContextCHROMIUM': {
+    'gen_cmd': False,
+    'extension': True,
+    'chromium': True,
+  },
 }
 
 
@@ -2225,9 +2231,11 @@ TEST_F(%(test_name)s, %(name)sInvalidArgs%(arg_index)d_%(value_index)d) {
     """Writes the GLES2 Implemention."""
     impl_func = func.GetInfo('impl_func')
     impl_decl = func.GetInfo('impl_decl')
+    gen_cmd = func.GetInfo('gen_cmd')
     if (func.can_auto_generate and
         (impl_func == None or impl_func == True) and
-        (impl_decl == None or impl_decl == True)):
+        (impl_decl == None or impl_decl == True) and
+        (gen_cmd == None or gen_cmd == True)):
       file.Write("%s %s(%s) {\n" %
                  (func.return_type, func.original_name,
                   func.MakeTypedOriginalArgString("")))
diff --git a/gpu/command_buffer/client/gles2_c_lib_autogen.h b/gpu/command_buffer/client/gles2_c_lib_autogen.h
index 9a75761..889a243 100644
--- a/gpu/command_buffer/client/gles2_c_lib_autogen.h
+++ b/gpu/command_buffer/client/gles2_c_lib_autogen.h
@@ -885,6 +885,10 @@ void GLES2WaitLatchCHROMIUM(GLuint latch_id) {
   GPU_CLIENT_LOG("WaitLatchCHROMIUM" << "(" << latch_id << ")");
   gles2::GetGLContext()->WaitLatchCHROMIUM(latch_id);
 }
+void GLES2RateLimitOffscreenContextCHROMIUM() {
+  GPU_CLIENT_LOG("RateLimitOffscreenContextCHROMIUM" << "(" << ")");
+  gles2::GetGLContext()->RateLimitOffscreenContextCHROMIUM();
+}
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_C_LIB_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 3810919..7bd07b4 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -1712,5 +1712,14 @@ void GLES2Implementation::RequestExtensionCHROMIUM(const char* extension) {
   helper_->SetBucketSize(kResultBucketId, 0);
 }
 
+void GLES2Implementation::RateLimitOffscreenContextCHROMIUM() {
+  // Wait if this would add too many rate limit tokens.
+  if (rate_limit_tokens_.size() == kMaxSwapBuffers) {
+    helper_->WaitForToken(rate_limit_tokens_.front());
+    rate_limit_tokens_.pop();
+  }
+  rate_limit_tokens_.push(helper_->InsertToken());
+}
+
 }  // namespace gles2
 }  // namespace gpu
diff --git a/gpu/command_buffer/client/gles2_implementation.h b/gpu/command_buffer/client/gles2_implementation.h
index 36f7dee2..3c25116 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -299,6 +299,7 @@ class GLES2Implementation {
   std::string last_error_;
 
   std::queue<int32> swap_buffers_tokens_;
+  std::queue<int32> rate_limit_tokens_;
 
   // pack alignment as last set by glPixelStorei
   GLint pack_alignment_;
diff --git a/gpu/command_buffer/client/gles2_implementation_autogen.h b/gpu/command_buffer/client/gles2_implementation_autogen.h
index bb392b0..97704a1 100644
--- a/gpu/command_buffer/client/gles2_implementation_autogen.h
+++ b/gpu/command_buffer/client/gles2_implementation_autogen.h
@@ -897,5 +897,7 @@ void WaitLatchCHROMIUM(GLuint latch_id) {
   helper_->WaitLatchCHROMIUM(latch_id);
 }
 
+void RateLimitOffscreenContextCHROMIUM();
+
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index 3ed88ad..f6bf440 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -109,6 +109,7 @@ void FeatureInfo::AddFeatures(const char* desired_features) {
   AddExtensionString("GL_CHROMIUM_strict_attribs");
   AddExtensionString("GL_CHROMIUM_latch");
   AddExtensionString("GL_CHROMIUM_swapbuffers_complete_callback");
+  AddExtensionString("GL_CHROMIUM_rate_limit_offscreen_context");
 
   // Only turn this feature on if it is requested. Not by default.
   if (desired_features && ext.Desire("GL_CHROMIUM_webglsl")) {