OOP-R crashes: Don't flush between begin/end raster

Flushing every single command succeeded in preventing crashes. Flushing
every raster command didn't succeed in preventing crashes.  Maybe
flushing everything but the raster commands will still prevent crashes?

Bug: 906453
Change-Id: I674ff93e03777b790fe840dfd9ae9a2fac82ee95
Reviewed-on: https://chromium-review.googlesource.com/c/1450472
Commit-Queue: ccameron <ccameron@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Reviewed-by: Victor Miura <vmiura@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628914}

gpu/command_buffer/service/raster_decoder.cc

@@ -367,6 +367,19 @@ class RasterDecoderImpl final : public RasterDecoder,
     return feature_info_->workarounds();
   }
 
+  void FlushToWorkAroundMacCrashes() {
+#if defined(OS_MACOSX)
+    // This function does aggressive flushes to work around crashes in the
+    // macOS OpenGL driver.
+    // https://crbug.com/906453
+    if (!flush_workaround_disabled_for_test_) {
+      if (gr_context())
+        gr_context()->flush();
+      api()->glFlushFn();
+    }
+#endif
+  }
+
   bool IsRobustnessSupported() {
     return has_robustness_extension_ &&
            shared_context_state_->context()
@@ -1116,18 +1129,6 @@ error::Error RasterDecoderImpl::DoCommandsImpl(unsigned int num_commands,
   int process_pos = 0;
   CommandId command = static_cast<CommandId>(0);
 
-#if defined(OS_MACOSX)
-  if (!flush_workaround_disabled_for_test_) {
-    // Flush before and after decoding commands.
-    // TODO(ccameron): This is to determine if this high frequency flushing
-    // affects crash rates.
-    // https://crbug.com/906453
-    if (gr_context())
-      gr_context()->flush();
-    api()->glFlushFn();
-  }
-#endif
-
   while (process_pos < num_entries && result == error::kNoError &&
          commands_to_process_--) {
     const unsigned int size = cmd_data->value_header.size;
@@ -1209,13 +1210,10 @@ error::Error RasterDecoderImpl::DoCommandsImpl(unsigned int num_commands,
       cmd_data += size;
     }
 
-#if defined(OS_MACOSX)
-    if (!flush_workaround_disabled_for_test_) {
-      if (gr_context())
-        gr_context()->flush();
-      api()->glFlushFn();
-    }
-#endif
+    // Workaround for https://crbug.com/906453: Flush after every command that
+    // is not between a BeginRaster and EndRaster.
+    if (!sk_surface_)
+      FlushToWorkAroundMacCrashes();
   }
 
   *entries_processed = process_pos;
@@ -1228,14 +1226,6 @@ error::Error RasterDecoderImpl::DoCommandsImpl(unsigned int num_commands,
   if (supports_oop_raster_)
     client_->ScheduleGrContextCleanup();
 
-#if defined(OS_MACOSX)
-  if (!flush_workaround_disabled_for_test_) {
-    if (gr_context())
-      gr_context()->flush();
-    api()->glFlushFn();
-  }
-#endif
-
   return result;
 }
 
@@ -2024,6 +2014,10 @@ void RasterDecoderImpl::DoBeginRasterCHROMIUM(
     GLboolean can_use_lcd_text,
     GLuint color_space_transfer_cache_id,
     const volatile GLbyte* key) {
+  // Workaround for https://crbug.com/906453: Flush before BeginRaster (the
+  // commands between BeginRaster and EndRaster will not flush).
+  FlushToWorkAroundMacCrashes();
+
   if (!gr_context()) {
     LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, "glBeginRasterCHROMIUM",
                        "chromium_raster_transport not enabled via attribs");