Peak GPU Memory Ablation Improved Size Controls

Update GpuMemoryAblationExperiment to have more fine grained controls
for setting the size of each ablation. Rather than there being 3 hard
coded sizes, the multiplier for the size is read in.

With setup to parse Finch parameters, and additional command line flag
for use with running experiments outside of Finch trials.

Bug: 908462
Change-Id: Ie6e03809f788334d15d20ba1756f94640d84bd81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2360572Reviewed-by: Jonathan Backer <backer@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803352}

gpu/ipc/service/gpu_memory_ablation_experiment.cc

@@ -7,7 +7,9 @@
 #include <algorithm>
 
 #include "base/bind.h"
+#include "base/metrics/field_trial_params.h"
 #include "base/sequenced_task_runner.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/time/time.h"
 #include "base/trace_event/common/trace_event_common.h"
 #include "components/viz/common/features.h"
@@ -21,6 +23,7 @@
 #include "gpu/ipc/service/gpu_memory_buffer_factory.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "third_party/skia/include/gpu/GrDirectContext.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface.h"
@@ -32,21 +35,8 @@ namespace gpu {
 const base::Feature kGPUMemoryAblationFeature{
     "GPUMemoryAblation", base::FEATURE_DISABLED_BY_DEFAULT};
 
-// TODO(jonross): Replace these feature flags with Field Trial Param lookup.
-const base::Feature kGPUMemoryAblationGPUSmall{
-    "GPUMemoryAblationGPUSmall", base::FEATURE_DISABLED_BY_DEFAULT};
-
-const base::Feature kGPUMemoryAblationGPUMedium{
-    "GPUMemoryAblationGPUMedium", base::FEATURE_DISABLED_BY_DEFAULT};
-
-const base::Feature kGPUMemoryAblationGPULarge{
-    "GPUMemoryAblationGPULarge", base::FEATURE_DISABLED_BY_DEFAULT};
-
-// The size to use when allocating images. The sizes vary based on the chosen
-// experiment.
-constexpr gfx::Size kSmallSize(256, 256);
-constexpr gfx::Size kMediumSize(256 * 4, 256 * 4);
-constexpr gfx::Size kLargeSize(256 * 8, 256 * 8);
+// Field Trial Parameter that defines the size of memory allocations.
+const char kGPUMemoryAblationFeatureSizeParam[] = "Size";
 
 // Image allocation parameters.
 constexpr viz::ResourceFormat kFormat = viz::ResourceFormat::RGBA_8888;
@@ -75,13 +65,6 @@ GpuMemoryAblationExperiment::GpuMemoryAblationExperiment(
     : channel_manager_(channel_manager), task_runner_(task_runner) {
   if (!GpuMemoryAblationExperiment::ExperimentSupported())
     init_status_ = Status::DISABLED;
-  if (base::FeatureList::IsEnabled(kGPUMemoryAblationGPUSmall)) {
-    size_ = kSmallSize;
-  } else if (base::FeatureList::IsEnabled(kGPUMemoryAblationGPUMedium)) {
-    size_ = kMediumSize;
-  } else if (base::FeatureList::IsEnabled(kGPUMemoryAblationGPULarge)) {
-    size_ = kLargeSize;
-  }
 }
 
 GpuMemoryAblationExperiment::~GpuMemoryAblationExperiment() {
@@ -219,6 +202,16 @@ bool GpuMemoryAblationExperiment::InitGpu(GpuChannelManager* channel_manager) {
   if (result != ContextResult::kSuccess)
     return false;
 
+  const int default_value = 0;
+  int arg_value = base::GetFieldTrialParamByFeatureAsInt(
+      kGPUMemoryAblationFeature, kGPUMemoryAblationFeatureSizeParam,
+      default_value);
+  if (arg_value == default_value)
+    return false;
+  int texture_size =
+      std::min(256 * arg_value, context_state_->gr_context()->maxTextureSize());
+  size_ = gfx::Size(texture_size, texture_size);
+
   std::unique_ptr<ui::ScopedMakeCurrent> scoped_current =
       ScopedMakeContextCurrent();
   if (!scoped_current)