Reland "[Read Anything] Set maximum side panel width during resizing."

This is a reland of commit 7fc7a9b

What changed: Use content_container rather than content_web_view for
the maximum width calculation of side panel. Content_container also
includes dev tools, while content_web_view does not. Side panel
computation should be based on the entire contents, including dev tools.

Original change's description:
> [Read Anything] Set maximum side panel width during resizing.
>
> Current side panel resizing rules:
> 1. The minimum browser window width is 500
>    (kMainBrowserContentsMinimumWidth).
> 2. The minimum side panel width is 320.
> 3. The side panel can be widened up until it leaves 500 - 320 = 180
>    in the main web contents.
>
> Proposed side panel resizing rules:
> 1. The minimum window width remains at its current 500.
> 2. The minimum main web contents width remains at its current 180.
> 3. At 500px, the side panel is 320 and the main web contents is
>    180px, as before the proposal.
> 4. Between window width = 500 to 820, the side panel remains at
>    320px and the main contents increases in width.
> 5. At window width > 820, side panel can now be widened. It cannot
>    go wider than a width that would keep the main contents at least
>    at 500.
>
> The motivation for this change is that the current behavior, which
> allows side panel to be resized up to leaving the main web contents
> at 180, even when the browser window size is very large:
> https://screenshot.googleplex.com/9Fr9axFE4hfJWFE. For Read Anything
> we would like to remove this possibility.
>
> For more context and alternatives, see
> https://docs.google.com/document/d/1qfuhKHWrveRc5UQ37KdFGMDvt2JypvyU_4h8ejNfips/edit#
>
> Bug: 1329585, 1266555
> Change-Id: I166760e168809db6400e12c5c359ef681c7879d3
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4000980
> Reviewed-by: Peter Boström <pbos@chromium.org>
> Commit-Queue: Abigail Klein <abigailbklein@google.com>
> Cr-Commit-Position: refs/heads/main@{#1076212}

Bug: 1329585, 1266555
Change-Id: Ic15fa8d951da9bb7b74675d33d112131477a5bb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4098251
Reviewed-by: Peter Boström <pbos@chromium.org>
Commit-Queue: Abigail Klein <abigailbklein@google.com>
Cr-Commit-Position: refs/heads/main@{#1082187}

chrome/browser/ui/views/side_panel/side_panel.cc

@@ -217,9 +217,8 @@ bool SidePanel::IsRightAligned() {
 }
 
 gfx::Size SidePanel::GetMinimumSize() const {
-  const int min_side_panel_contents_width = 320;
   const int min_height = 0;
-  return gfx::Size(min_side_panel_contents_width + kBorderInsets.width(),
+  return gfx::Size(min_side_panel_contents_width_ + kBorderInsets.width(),
                    min_height);
 }
 
@@ -257,8 +256,21 @@ void SidePanel::OnResize(int resize_amount, bool done_resizing) {
     starting_width_on_resize_ = -1;
   }
   const int minimum_width = GetMinimumSize().width();
-  if (proposed_width < minimum_width) {
+  // The side panel may be resized up to leaving the main contents at
+  // kMainBrowserContentsMinimumWidth.
+  DCHECK_EQ(browser_view_->GetMinimumSize().width(),
+            BrowserViewLayout::kMainBrowserContentsMinimumWidth);
+  const int maximum_width = width() +
+                            browser_view_->contents_container()->width() -
+                            BrowserViewLayout::kMainBrowserContentsMinimumWidth;
+  // Side panel must stay at minimum width if either:
+  // a) The proposed width is less than the minimum.
+  // b) There is not enough room for the side panel to be wider than the
+  //    minimum.
+  if (proposed_width < minimum_width || maximum_width < minimum_width) {
     proposed_width = minimum_width;
+  } else if (proposed_width > maximum_width) {
+    proposed_width = maximum_width;
   }
   if (width() != proposed_width) {
     SetPanelWidth(proposed_width);

chrome/browser/ui/views/side_panel/side_panel.h

@@ -37,6 +37,9 @@ class SidePanel : public views::AccessiblePaneView,
   HorizontalAlignment GetHorizontalAlignment();
   bool IsRightAligned();
   gfx::Size GetMinimumSize() const override;
+  void SetMinimumSidePanelContentsWidthForTesting(int width) {
+    min_side_panel_contents_width_ = width;
+  }
 
   // views::ResizeAreaDelegate:
   void OnResize(int resize_amount, bool done_resizing) override;
@@ -72,6 +75,8 @@ class SidePanel : public views::AccessiblePaneView,
 
   // Observes and listens to side panel alignment changes.
   PrefChangeRegistrar pref_change_registrar_;
+
+  int min_side_panel_contents_width_ = 320;
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_SIDE_PANEL_SIDE_PANEL_H_

chrome/browser/ui/views/side_panel/side_panel_coordinator_unittest.cc

@@ -119,6 +119,19 @@ class SidePanelCoordinatorTest : public TestWithBrowserView {
     return coordinator_->header_combobox_ != nullptr;
   }
 
+  void SetBrowserViewWidth(const int width) {
+    // If browser window is maximized then explicitly restore it, as otherwise
+    // the SetBounds call would be a no-op.
+    // TODO(crbug.com/1393153): Fix this on lacros builds and remove buildflag.
+#if !BUILDFLAG(IS_CHROMEOS_LACROS)
+    if (browser_view()->IsMaximized())
+      browser_view()->Restore();
+#endif
+
+    browser_view()->SetBounds(
+        gfx::Rect(width, browser_view()->GetBounds().height()));
+  }
+
  protected:
   raw_ptr<SidePanelCoordinator> coordinator_;
   raw_ptr<SidePanelRegistry> global_registry_;
@@ -142,8 +155,22 @@ TEST_F(SidePanelCoordinatorTest, ChangeSidePanelWidth) {
   // Set side panel to right-aligned
   browser_view()->GetProfile()->GetPrefs()->SetBoolean(
       prefs::kSidePanelHorizontalAlignment, true);
+
+  // The side panel can only be widened when the browser main web contents width
+  // is greater than |BrowserViewLayout::kMainBrowserContentsMinimumWidth|,
+  // which is 500. Therefore the side panel can only be widened when the total
+  // browser view width is greater than the minimum side panel contents width +
+  // 500. The browser view maximum width is constrained by the display maximum,
+  // which is 800 on win32 and ChromeOS.
+  // Therefore, we set the browser view width to be 800 and we reduce the side
+  // panel width to 100 so that it can be widened and shrunk.
+  SetBrowserViewWidth(800);
+  browser_view()
+      ->unified_side_panel()
+      ->SetMinimumSidePanelContentsWidthForTesting(100);
+
   coordinator_->Toggle();
-  const int starting_width = 500;
+  const int starting_width = 200;
   browser_view()->unified_side_panel()->SetPanelWidth(starting_width);
   views::test::RunScheduledLayout(browser_view());
   EXPECT_EQ(browser_view()->unified_side_panel()->width(), starting_width);
@@ -168,8 +195,21 @@ TEST_F(SidePanelCoordinatorTest, ChangeSidePanelWidth) {
 }
 
 TEST_F(SidePanelCoordinatorTest, ChangeSidePanelWidthMaxMin) {
+  // The side panel can only be widened when the browser main web contents width
+  // is greater than |BrowserViewLayout::kMainBrowserContentsMinimumWidth|,
+  // which is 500. Therefore the side panel can only be widened when the total
+  // browser view width is greater than the minimum side panel contents width +
+  // 500. The browser view maximum width is constrained by the display maximum,
+  // which is 800 on win32 and ChromeOS.
+  // Therefore, we set the browser view width to be 800 and we reduce the side
+  // panel width to 100 so that it can be widened and shrunk.
+  SetBrowserViewWidth(800);
+  browser_view()
+      ->unified_side_panel()
+      ->SetMinimumSidePanelContentsWidthForTesting(100);
+
   coordinator_->Toggle();
-  const int starting_width = 500;
+  const int starting_width = 200;
   browser_view()->unified_side_panel()->SetPanelWidth(starting_width);
   views::test::RunScheduledLayout(browser_view());
   EXPECT_EQ(browser_view()->unified_side_panel()->width(), starting_width);
@@ -184,22 +224,32 @@ TEST_F(SidePanelCoordinatorTest, ChangeSidePanelWidthMaxMin) {
 
   browser_view()->unified_side_panel()->OnResize(-large_increment, true);
   views::test::RunScheduledLayout(browser_view());
-  BrowserViewLayout* layout_manager =
-      static_cast<BrowserViewLayout*>(browser_view()->GetLayoutManager());
-  const int min_web_contents_width =
-      layout_manager->GetMinWebContentsWidthForTesting();
-  EXPECT_EQ(browser_view()->contents_web_view()->width(),
-            min_web_contents_width);
+  EXPECT_GT(browser_view()->unified_side_panel()->width(), starting_width);
+  EXPECT_EQ(browser_view()->contents_container()->width(),
+            BrowserViewLayout::kMainBrowserContentsMinimumWidth);
 }
 
 TEST_F(SidePanelCoordinatorTest, ChangeSidePanelWidthRTL) {
+  // The side panel can only be widened when the browser main web contents width
+  // is greater than |BrowserViewLayout::kMainBrowserContentsMinimumWidth|,
+  // which is 500. Therefore the side panel can only be widened when the total
+  // browser view width is greater than the minimum side panel contents width +
+  // 500. The browser view maximum width is constrained by the display maximum,
+  // which is 800 on win32 and ChromeOS.
+  // Therefore, we set the browser view width to be 800 and we reduce the side
+  // panel width to 100 so that it can be widened and shrunk.
+  SetBrowserViewWidth(800);
+  browser_view()
+      ->unified_side_panel()
+      ->SetMinimumSidePanelContentsWidthForTesting(100);
+
   // Set side panel to right-aligned
   browser_view()->GetProfile()->GetPrefs()->SetBoolean(
       prefs::kSidePanelHorizontalAlignment, true);
   // Set UI direction to LTR
   base::i18n::SetRTLForTesting(false);
   coordinator_->Toggle();
-  const int starting_width = 500;
+  const int starting_width = 200;
   browser_view()->unified_side_panel()->SetPanelWidth(starting_width);
   views::test::RunScheduledLayout(browser_view());
   EXPECT_EQ(browser_view()->unified_side_panel()->width(), starting_width);
@@ -223,38 +273,79 @@ TEST_F(SidePanelCoordinatorTest, ChangeSidePanelWidthRTL) {
 }
 
 TEST_F(SidePanelCoordinatorTest, ChangeSidePanelWidthWindowResize) {
+  // The side panel can only be widened when the browser main web contents width
+  // is greater than |BrowserViewLayout::kMainBrowserContentsMinimumWidth|,
+  // which is 500. Therefore the side panel can only be widened when the total
+  // browser view width is greater than the minimum side panel contents width +
+  // 500. The browser view maximum width is constrained by the display maximum,
+  // which is 800 on win32 and ChromeOS.
+  // Therefore, we set the browser view width to be 800 and we reduce the side
+  // panel width to 100 so that it can be widened and shrunk.
+  SetBrowserViewWidth(800);
+  browser_view()
+      ->unified_side_panel()
+      ->SetMinimumSidePanelContentsWidthForTesting(100);
+
   coordinator_->Toggle();
-  const int starting_width = 500;
+  const int starting_width = 200;
   browser_view()->unified_side_panel()->SetPanelWidth(starting_width);
   views::test::RunScheduledLayout(browser_view());
   EXPECT_EQ(browser_view()->unified_side_panel()->width(), starting_width);
 
   // Shrink browser window enough that side panel should also shrink in
   // observance of web contents minimum width.
-  gfx::Rect original_bounds(browser_view()->GetBounds());
-  gfx::Size new_size(starting_width, starting_width);
-  gfx::Rect new_bounds(original_bounds);
-  new_bounds.set_size(new_size);
-  // Explicitly restore the browser window on ChromeOS, as it would otherwise
-  // be maximized and the SetBounds call would be a no-op.
-#if BUILDFLAG(IS_CHROMEOS_ASH)
-  browser_view()->Restore();
-#endif
-  browser_view()->SetBounds(new_bounds);
-  EXPECT_LT(browser_view()->unified_side_panel()->width(), starting_width);
-  BrowserViewLayout* layout_manager =
+  const int original_width = browser_view()->GetBounds().width();
+  SetBrowserViewWidth(starting_width);
+  EXPECT_EQ(browser_view()->unified_side_panel()->width(),
+            browser_view()->unified_side_panel()->GetMinimumSize().width());
+  BrowserViewLayout* const layout_manager =
       static_cast<BrowserViewLayout*>(browser_view()->GetLayoutManager());
   const int min_web_contents_width =
       layout_manager->GetMinWebContentsWidthForTesting();
-  EXPECT_EQ(browser_view()->contents_web_view()->width(),
+  EXPECT_EQ(browser_view()->contents_container()->width(),
             min_web_contents_width);
 
   // Return browser window to original size, side panel should also return to
   // size prior to window resize.
-  browser_view()->SetBounds(original_bounds);
+  SetBrowserViewWidth(original_width);
   EXPECT_EQ(browser_view()->unified_side_panel()->width(), starting_width);
 }
 
+TEST_F(SidePanelCoordinatorTest, ChangeSidePanelWidthSmallWindow) {
+  SetBrowserViewWidth(500);
+  browser_view()
+      ->unified_side_panel()
+      ->SetMinimumSidePanelContentsWidthForTesting(100);
+  coordinator_->Toggle();
+  const int starting_width = 200;
+  const int min_side_panel_width =
+      browser_view()->unified_side_panel()->GetMinimumSize().width();
+  browser_view()->unified_side_panel()->SetPanelWidth(starting_width);
+  views::test::RunScheduledLayout(browser_view());
+  EXPECT_EQ(browser_view()->unified_side_panel()->width(),
+            min_side_panel_width);
+
+  // Attempt to resize the side panel, side panel should not be able to resized.
+  const int increment = 50;
+  browser_view()->unified_side_panel()->OnResize(increment, true);
+  views::test::RunScheduledLayout(browser_view());
+  EXPECT_EQ(browser_view()->unified_side_panel()->width(),
+            min_side_panel_width);
+  BrowserViewLayout* const layout_manager =
+      static_cast<BrowserViewLayout*>(browser_view()->GetLayoutManager());
+  const int min_web_contents_width =
+      layout_manager->GetMinWebContentsWidthForTesting();
+  EXPECT_EQ(browser_view()->contents_container()->width(),
+            min_web_contents_width);
+
+  browser_view()->unified_side_panel()->OnResize(-increment, true);
+  views::test::RunScheduledLayout(browser_view());
+  EXPECT_EQ(browser_view()->unified_side_panel()->width(),
+            min_side_panel_width);
+  EXPECT_EQ(browser_view()->contents_container()->width(),
+            min_web_contents_width);
+}
+
 TEST_F(SidePanelCoordinatorTest, ChangeSidePanelAlignment) {
   browser_view()->GetProfile()->GetPrefs()->SetBoolean(
       prefs::kSidePanelHorizontalAlignment, true);