Make LayerScrollOffsetDelegate updates consistent.

android_webview/browser/browser_view_renderer.cc

Index: android_webview/browser/browser_view_renderer.cc
diff --git a/android_webview/browser/browser_view_renderer.cc b/android_webview/browser/browser_view_renderer.cc
index 937ed13259c1de75bde6d7c190b38566373c5351..e774080cb9f991d2f7319cc9d1ecf71fdf28ec05 100644
--- a/android_webview/browser/browser_view_renderer.cc
+++ b/android_webview/browser/browser_view_renderer.cc
@@ -10,6 +10,7 @@
 #include "base/android/jni_android.h"
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
+#include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "content/public/browser/android/synchronous_compositor.h"
@@ -54,6 +55,27 @@ class AutoResetWithLock {
   DISALLOW_COPY_AND_ASSIGN(AutoResetWithLock);
 };
 
+class TracedValue : public base::debug::ConvertableToTraceFormat {
+ public:
+  explicit TracedValue(base::Value* value) : value_(value) {}
+  static scoped_refptr<base::debug::ConvertableToTraceFormat> FromValue(
+      base::Value* value) {
+    return scoped_refptr<base::debug::ConvertableToTraceFormat>(
+        new TracedValue(value));
+  }
+  virtual void AppendAsTraceFormat(std::string* out) const OVERRIDE {
+    std::string tmp;
+    base::JSONWriter::Write(value_.get(), &tmp);
+    *out += tmp;
+  }
+
+ private:
+  virtual ~TracedValue() {}
+  scoped_ptr<base::Value> value_;
+
+  DISALLOW_COPY_AND_ASSIGN(TracedValue);
+};
+
 }  // namespace
 
 BrowserViewRenderer::BrowserViewRenderer(
@@ -351,25 +373,6 @@ void BrowserViewRenderer::DidUpdateContent() {
     client_->OnNewPicture();
 }
 
-void BrowserViewRenderer::SetMaxRootLayerScrollOffset(
-    gfx::Vector2dF new_value_dip) {
-  if (!ui_task_runner_->BelongsToCurrentThread()) {
-    ui_task_runner_->PostTask(
-        FROM_HERE,
-        base::Bind(&BrowserViewRenderer::SetMaxRootLayerScrollOffset,
-                   ui_thread_weak_ptr_,
-                   new_value_dip));
-    return;
-  }
-  DCHECK_GT(dip_scale_, 0);
-
-  max_scroll_offset_dip_ = new_value_dip;
-  DCHECK_LE(0, max_scroll_offset_dip_.x());
-  DCHECK_LE(0, max_scroll_offset_dip_.y());
-
-  client_->SetMaxContainerViewScrollOffset(max_scroll_offset());
-}
-
 void BrowserViewRenderer::SetTotalRootLayerScrollOffset(
     gfx::Vector2dF scroll_offset_dip) {
   if (!ui_task_runner_->BelongsToCurrentThread()) {
@@ -380,6 +383,12 @@ void BrowserViewRenderer::SetTotalRootLayerScrollOffset(
                    scroll_offset_dip));
     return;
   }
+  TRACE_EVENT2("android_webview",
+               "BrowserViewRenderer::SetTotalRootLayerScrollOffset",
+               "x",
+               scroll_offset_dip.x(),
+               "y",
+               scroll_offset_dip.y());
 
   {
     base::AutoLock lock(scroll_offset_dip_lock_);
@@ -407,10 +416,8 @@ void BrowserViewRenderer::SetTotalRootLayerScrollOffset(
 
   DCHECK(0 <= scroll_offset.x());
   DCHECK(0 <= scroll_offset.y());
-  // Disabled because the conditions are being violated while running
-  // AwZoomTest.testMagnification, see http://crbug.com/340648
-  // DCHECK(scroll_offset.x() <= max_offset.x());
-  // DCHECK(scroll_offset.y() <= max_offset.y());
+  DCHECK(scroll_offset.x() <= max_offset.x());
+  DCHECK(scroll_offset.y() <= max_offset.y());
 
   client_->ScrollContainerViewTo(scroll_offset);
 }
@@ -429,38 +436,64 @@ bool BrowserViewRenderer::IsExternalFlingActive() const {
   return client_->IsFlingActive();
 }
 
-void BrowserViewRenderer::SetRootLayerPageScaleFactorAndLimits(
+void BrowserViewRenderer::UpdateRootLayerState(
+    const gfx::Vector2dF& total_scroll_offset_dip,
+    const gfx::Vector2dF& max_scroll_offset_dip,
+    const gfx::SizeF& scrollable_size_dip,
     float page_scale_factor,
     float min_page_scale_factor,
     float max_page_scale_factor) {
   if (!ui_task_runner_->BelongsToCurrentThread()) {
     ui_task_runner_->PostTask(
         FROM_HERE,
-        base::Bind(&BrowserViewRenderer::SetRootLayerPageScaleFactorAndLimits,
+        base::Bind(&BrowserViewRenderer::UpdateRootLayerState,
                    ui_thread_weak_ptr_,
+                   total_scroll_offset_dip,
+                   max_scroll_offset_dip,
+                   scrollable_size_dip,
                    page_scale_factor,
                    min_page_scale_factor,
                    max_page_scale_factor));
     return;
   }
+  {
+    scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue);

[boliu, 2014/04/30 05:48:42]

Isn't this gonna be slow in production?

I think if you factor out this into a function, then TRACE_EVENT won't call it
if trace is not on, and safe some cpu cycles.

Also there are other kind of traces like counters, which might be a better fit,
though some of these values might already be traced in cc.

[mkosiba (inactive), 2014/05/01 11:13:25]

Done. The main reason for adding these is that we're getting scrolling-related
bugs again so having a bit more tracing here should make figuring out the issue
from traces folks upload a bit easier.

+    state->SetDouble("total_scroll_offset_dip.x", total_scroll_offset_dip.x());
+    state->SetDouble("total_scroll_offset_dip.y", total_scroll_offset_dip.y());
+
+    state->SetDouble("max_scroll_offset_dip.x", max_scroll_offset_dip.x());
+    state->SetDouble("max_scroll_offset_dip.y", max_scroll_offset_dip.y());
+
+    state->SetDouble("scrollable_size_dip.width", scrollable_size_dip.width());
+    state->SetDouble("scrollable_size_dip.height",
+                     scrollable_size_dip.height());
+
+    state->SetDouble("page_scale_factor", page_scale_factor);
+    state->SetDouble("min_page_scale_factor", min_page_scale_factor);
+    state->SetDouble("max_page_scale_factor", max_page_scale_factor);
+
+    TRACE_EVENT_INSTANT1("android_webview",
+                         "BrowserViewRenderer::UpdateRootLayerState",
+                         TRACE_EVENT_SCOPE_THREAD,
+                         "state",
+                         TracedValue::FromValue(state.release()));
+  }
+
+  DCHECK_GT(dip_scale_, 0);
+
+  max_scroll_offset_dip_ = max_scroll_offset_dip;
+  DCHECK_LE(0, max_scroll_offset_dip_.x());
+  DCHECK_LE(0, max_scroll_offset_dip_.y());
+
   page_scale_factor_ = page_scale_factor;
   DCHECK_GT(page_scale_factor_, 0);
-  client_->SetPageScaleFactorAndLimits(
-      page_scale_factor, min_page_scale_factor, max_page_scale_factor);
-  client_->SetMaxContainerViewScrollOffset(max_scroll_offset());
-}
 
-void BrowserViewRenderer::SetRootLayerScrollableSize(
-    gfx::SizeF scrollable_size) {
-  if (!ui_task_runner_->BelongsToCurrentThread()) {
-    ui_task_runner_->PostTask(
-        FROM_HERE,
-        base::Bind(&BrowserViewRenderer::SetRootLayerScrollableSize,
-                   ui_thread_weak_ptr_,
-                   scrollable_size));
-    return;
-  }
-  client_->SetContentsSize(scrollable_size);
+  client_->UpdateScrollState(max_scroll_offset(),
+                             scrollable_size_dip,
+                             page_scale_factor,
+                             min_page_scale_factor,
+                             max_page_scale_factor);
+  SetTotalRootLayerScrollOffset(total_scroll_offset_dip);
 }
 
 void BrowserViewRenderer::DidOverscroll(gfx::Vector2dF accumulated_overscroll,