cc: Implement shared worker contexts. (v1)

cc/raster/one_copy_tile_task_worker_pool.cc

Index: cc/raster/one_copy_tile_task_worker_pool.cc
diff --git a/cc/raster/one_copy_tile_task_worker_pool.cc b/cc/raster/one_copy_tile_task_worker_pool.cc
index b2f8c11309d118863c4e384f951a9ed8eb486899..eb7a94bed1def77533b498639748679446485489 100644
--- a/cc/raster/one_copy_tile_task_worker_pool.cc
+++ b/cc/raster/one_copy_tile_task_worker_pool.cc
@@ -112,15 +112,18 @@ OneCopyTileTaskWorkerPool::StagingBuffer::~StagingBuffer() {
 void OneCopyTileTaskWorkerPool::StagingBuffer::DestroyGLResources(
     gpu::gles2::GLES2Interface* gl) {
   if (query_id) {
-    gl->DeleteQueriesEXT(1, &query_id);
+    if (gl)
+      gl->DeleteQueriesEXT(1, &query_id);
     query_id = 0;
   }
   if (image_id) {
-    gl->DestroyImageCHROMIUM(image_id);
+    if (gl)
+      gl->DestroyImageCHROMIUM(image_id);
     image_id = 0;
   }
   if (texture_id) {
-    gl->DeleteTextures(1, &texture_id);
+    if (gl)
+      gl->DeleteTextures(1, &texture_id);
     texture_id = 0;
   }
 }
@@ -420,53 +423,53 @@ void OneCopyTileTaskWorkerPool::PlaybackAndCopyOnWorkerThread(
     ContextProvider::ScopedContextLock scoped_context(context_provider);
 
     gpu::gles2::GLES2Interface* gl = scoped_context.ContextGL();
-    DCHECK(gl);
-
-    unsigned image_target = resource_provider_->GetImageTextureTarget(
-        resource_provider_->memory_efficient_texture_format());
-
-    // Create and bind staging texture.
-    if (!staging_buffer->texture_id) {
-      gl->GenTextures(1, &staging_buffer->texture_id);
-      gl->BindTexture(image_target, staging_buffer->texture_id);
-      gl->TexParameteri(image_target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-      gl->TexParameteri(image_target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-      gl->TexParameteri(image_target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-      gl->TexParameteri(image_target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-    } else {
-      gl->BindTexture(image_target, staging_buffer->texture_id);
-    }
+    if (gl) {
+      unsigned image_target = resource_provider_->GetImageTextureTarget(
+          resource_provider_->memory_efficient_texture_format());
+
+      // Create and bind staging texture.
+      if (!staging_buffer->texture_id) {
+        gl->GenTextures(1, &staging_buffer->texture_id);
+        gl->BindTexture(image_target, staging_buffer->texture_id);
+        gl->TexParameteri(image_target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        gl->TexParameteri(image_target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+        gl->TexParameteri(image_target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        gl->TexParameteri(image_target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+      } else {
+        gl->BindTexture(image_target, staging_buffer->texture_id);
+      }
 
-    // Create and bind image.
-    if (!staging_buffer->image_id) {
-      if (staging_buffer->gpu_memory_buffer) {
-        staging_buffer->image_id = gl->CreateImageCHROMIUM(
-            staging_buffer->gpu_memory_buffer->AsClientBuffer(),
-            staging_buffer->size.width(), staging_buffer->size.height(),
-            GLInternalFormat(
-                resource_provider_->memory_efficient_texture_format()));
+      // Create and bind image.
+      if (!staging_buffer->image_id) {
+        if (staging_buffer->gpu_memory_buffer) {
+          staging_buffer->image_id = gl->CreateImageCHROMIUM(
+              staging_buffer->gpu_memory_buffer->AsClientBuffer(),
+              staging_buffer->size.width(), staging_buffer->size.height(),
+              GLInternalFormat(
+                  resource_provider_->memory_efficient_texture_format()));
+          gl->BindTexImage2DCHROMIUM(image_target, staging_buffer->image_id);
+        }
+      } else {
+        gl->ReleaseTexImage2DCHROMIUM(image_target, staging_buffer->image_id);
         gl->BindTexImage2DCHROMIUM(image_target, staging_buffer->image_id);
       }
-    } else {
-      gl->ReleaseTexImage2DCHROMIUM(image_target, staging_buffer->image_id);
-      gl->BindTexImage2DCHROMIUM(image_target, staging_buffer->image_id);
-    }
 
-    // Unbind staging texture.
-    gl->BindTexture(image_target, 0);
+      // Unbind staging texture.
+      gl->BindTexture(image_target, 0);
 
-    if (resource_provider_->use_sync_query()) {
-      if (!staging_buffer->query_id)
-        gl->GenQueriesEXT(1, &staging_buffer->query_id);
+      if (resource_provider_->use_sync_query()) {
+        if (!staging_buffer->query_id)
+          gl->GenQueriesEXT(1, &staging_buffer->query_id);
 
 #if defined(OS_CHROMEOS)
-      // TODO(reveman): This avoids a performance problem on some ChromeOS
-      // devices. This needs to be removed to support native GpuMemoryBuffer
-      // implementations. crbug.com/436314
-      gl->BeginQueryEXT(GL_COMMANDS_ISSUED_CHROMIUM, staging_buffer->query_id);
+        // TODO(reveman): This avoids a performance problem on some ChromeOS
+        // devices. This needs to be removed to support native GpuMemoryBuffer
+        // implementations. crbug.com/436314
+        gl->BeginQueryEXT(GL_COMMANDS_ISSUED_CHROMIUM,
+                          staging_buffer->query_id);
 #else
-      gl->BeginQueryEXT(GL_COMMANDS_COMPLETED_CHROMIUM,
-                        staging_buffer->query_id);
+        gl->BeginQueryEXT(GL_COMMANDS_COMPLETED_CHROMIUM,
+                          staging_buffer->query_id);
 #endif
     }
 
@@ -511,6 +514,7 @@ void OneCopyTileTaskWorkerPool::PlaybackAndCopyOnWorkerThread(
 
     // Barrier to sync worker context output to cc context.
     gl->OrderingBarrierCHROMIUM();
+    }
   }
 
   staging_buffer->last_usage = base::TimeTicks::Now();
@@ -548,32 +552,32 @@ OneCopyTileTaskWorkerPool::AcquireStagingBuffer(const Resource* resource,
   ContextProvider::ScopedContextLock scoped_context(context_provider);
 
   gpu::gles2::GLES2Interface* gl = scoped_context.ContextGL();
-  DCHECK(gl);
-
-  // Check if any busy buffers have become available.
-  if (resource_provider_->use_sync_query()) {
-    while (!busy_buffers_.empty()) {
-      if (!CheckForQueryResult(gl, busy_buffers_.front()->query_id))
-        break;
+  if (gl) {
+    // Check if any busy buffers have become available.
+    if (resource_provider_->use_sync_query()) {
+      while (!busy_buffers_.empty()) {
+        if (!CheckForQueryResult(gl, busy_buffers_.front()->query_id))
+          break;
 
-      free_buffers_.push_back(busy_buffers_.take_front());
+        free_buffers_.push_back(busy_buffers_.take_front());
+      }
     }
-  }
 
-  // Wait for number of non-free buffers to become less than the limit.
-  while ((buffers_.size() - free_buffers_.size()) >= max_staging_buffers_) {
-    // Stop when there are no more busy buffers to wait for.
-    if (busy_buffers_.empty())
-      break;
+    // Wait for number of non-free buffers to become less than the limit.
+    while ((buffers_.size() - free_buffers_.size()) >= max_staging_buffers_) {
+      // Stop when there are no more busy buffers to wait for.
+      if (busy_buffers_.empty())
+        break;
 
-    if (resource_provider_->use_sync_query()) {
-      WaitForQueryResult(gl, busy_buffers_.front()->query_id);
-      free_buffers_.push_back(busy_buffers_.take_front());
-    } else {
-      // Fall-back to glFinish if CHROMIUM_sync_query is not available.
-      gl->Finish();
-      while (!busy_buffers_.empty())
+      if (resource_provider_->use_sync_query()) {
+        WaitForQueryResult(gl, busy_buffers_.front()->query_id);
         free_buffers_.push_back(busy_buffers_.take_front());
+      } else {
+        // Fall-back to glFinish if CHROMIUM_sync_query is not available.
+        gl->Finish();
+        while (!busy_buffers_.empty())
+          free_buffers_.push_back(busy_buffers_.take_front());
+      }
     }
   }
 
@@ -684,7 +688,6 @@ void OneCopyTileTaskWorkerPool::ReleaseBuffersNotUsedSince(
     ContextProvider::ScopedContextLock scoped_context(context_provider);
 
     gpu::gles2::GLES2Interface* gl = scoped_context.ContextGL();
-    DCHECK(gl);
 
     // Note: Front buffer is guaranteed to be LRU so we can stop releasing
     // buffers as soon as we find a buffer that has been used since |time|.